Read the following passage and choose the best answer for each blank.

The World Wide Fund for Nature (WWF) is an international (26) _____- governmental organization for the (27) _____, research, and restoration of the environment. The organization was (28) _____ as a charitable trust on September 11, 1961, in Morges, Switzerland, under the name World Wildlife Fund. It was an initiative of Julian Huxley and Max Nicholson.It is the world's largest independent conservation organization with over 5 million (29) _____ worldwide, working in more (30) _____ 90 countries, supporting 100 conservation and environmental projects around the world. It is a charity, with (31) ____ 9% of its funding coming from voluntary (32) ___ by private individuals and businesses.The group says its mission is "to halt and reverse the (33) _____ of our environment". Currently, much of its work focuses on the conservation of three biomes that contain most of the world's biodiversity: forests, freshwater ecosystems, and oceans and coasts. Among other issues, it is also concerned (34) _____ endangered species, pollution, and climate change. The organization (35) ____ more than 20 field projects worldwide. In the last few years, the organization set up offices and operations around the world.

(30) _____

Choose the best answer

Nearly 200 of the 1500 native plant species in Hawaii are at risk of going extinct in the near future because they have been (1) ____ to such low numbers. Approximately 90 percent of Hawaii's plants are found nowhere else in the world but they are (2) ____ by alien invasive species such as feral goats, pigs, rodents and non- (3) ____ plants. The Hawaii Rare Plant Restoration Group is striving to (4) ____ the extinction of the 182 rare Hawaiian plants with fewer than 50 individuals remaining in the (5) ____. Since 1990, (6) ____ a result of their “Plant Extinction Prevention Program‟, sixteen species have been brought into (7) ____ and three species have been reintroduced. Invasive weeds have been removed in key areas and fencing put up in order to (8) ____ plants in the wild.

In the future the Hawaii Rare Plant Restoration Program aims (9) ____ collecting genetic material from the remaining plants in the wild for storage as a safety net for the future. They also aim to manage wild populations and where possible reintroduce species into (10) ____.

(6) ____

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. 
       In “How many hours does it take to make a friend?” (2018), Jeffrey A. Hall describes the types of encounters that build a friendship.
       His study found that hours of time spent together was linked with closer friendships, as was time spent enjoying leisure activities together. Specifically, he found that the chance of making a “casual friend,” as opposed to a mere acquaintance, was greater than 50 percent when people spent approximately 43 hours together within three weeks of meeting. He further found that casual friends evolve into friends at some point between 57 hours after three weeks, and 164 hours over three months. Hall's research also demonstrated, however, that when it comes to time spent developing friendships, quality is more important than quantity. And when it comes to conversation, topics matter. When it comes to building quality relationships, the duration of conversation is not as important as the content. Meaningful conversation is the key to bonding with others. 
       Hall found that when it comes to developing friendships, sharing daily life through catching up and joking around promotes closeness; small talk does not. Consider the inane topics that often come up when you are trapped in an elevator with an acquaintance. Discussing the weather or speculating on how many stops you will make before finally reaching the lobby does not facilitate bonding. Nor does mere proximity. Hall found that obligatory time spent together, such as in a classroom or workplace, does not promote closeness. Friendships require an efficient use of time together. Someone who remembers the details of your life and asks questions about your family, your job, your latest vacation, etc., is much more likely on his or her way to becoming someone you consider a friend, as opposed to an acquaintance.

Which best serves as the title for the passage?

Choose the best answer

No more polar bear?

We all know that the Earth is growing warmer and warmer. This problem is called “global warming”. We also know that global warming is causing a lot of problems. Ocean levels are getting higher and higher. Because ocean levels are getting higher, storms are getting stronger and stronger. This list of problems goes on and on.

Animals are suffering a lot because of global warming. Polar bears are suffering more than most animals. This is because polar bears live in the North Pole. In the North Pole, global warming is making ice melt. Polar bears hunt from large pieces of floating ice. They jump off the ice and hunt for food. Polar bears have to swim and find these floating pieces of ice. These days, they have to swim farther to find the floating ice. Many of them don’t have enough energy. They get too tired, and they die in the water.

Polar bears are suffering because of other problems, too. Pollution makes their water dirty. Many countries go to the North Pole to look for oil and gas, and they damage the environment of the bears. In addition, when ships sail through the North Pole, they cause a lot of damage. Finally, people hunt and kill too many polar bears. However, melting ice is definitely the biggest problem.

Right now, there are about 25,000 polar bears in the world. If global warming continues, there may be only about 12,000 in the year 2050. By the year 2080, that number might be much smaller.

It is important to study polar bears. When we learn about polar bears, we also learn about the health of the North Pole. If polar bears are doing well, then the environment in the North Pole is probably healthy. If polar bears are suffering then there are probably serious problems in the North Pole.

Right now, governments around the world are working to help polar bears. There are new laws that protect polar bears. However, if global warming continues to get worse, polar bears may disappear forever.

Which of the following has the same meaning as the last sentence of the first paragraph?

Read the passage and choose the best answer to compete each of the statements that follow
The hippopotamus is the third largest land animal, smaller only than the elephant and the rhinoceros. Its name comes from two Greek words which mean "river horse". The long name of this animal is often shortened to the easier to handle term "hippo."
The hippo has a natural affinity for the water. It does not float on top of the water; instead, it can easily walk along the bottom of a body of water. The hippo commonly remains underwater for three to five minutes and has been known to stay under for up to half an hour before coming up for air.
In spite of its name, the hippo has relatively little in common with the horse and instead has a number of interesting similarities in common with the whale. When a hippo comes up after a stay at the bottom of a lake or river, it releases air through a blowhole, just like a whale. In addition, the hippo resembles the whale in that they both have thick layers of blubber for protection and they are almost completely hairless.

It can be inferred from the passage that the hippopotamus is commonly called a hippo because the word "hippo" is_____________

Read the passage and answer the questions.

During my last couple of years as a student here at Union High, I have noticed that there is nothing to do during our occasional free periods. Hanging around in the hallways or in the library with friends isn't productive or relaxing. The student body council noticed this as well and brought it to the attention of Mr. Swanson and the rest of the faculty. A meeting to discuss the issue occurred last Friday, February 10th, in the all - school meeting room.

The faculty not only agreed that there wasn't much to do during these free periods, but also seemed determined to find a solution. The student body council and the faculty talked about different ideas for a long time. The faculty had noticed that some students don't like using their free periods for studying. Instead, they spend their time disrupting the students who want to study by being noisy in the library. By the end of the meeting, the faculty had decided to put a pool table and a ping pong table in our student lobby at the start of next semester.

I know some people will be concerned about getting their work done with these potential distractions, but I believe this will help us all in enjoying our time at school. I agree that it's important to complete our work but it is just as important to enjoy ourselves and to relax with our friends. School is already such a stressful place. It makes many students feel worried and anxious. We want our school to be a friendly place so that students want to come every day. Students should remember that this change will make the library a lot quieter. Because of this, the students who want to study will be able to do so in peace.

To all the students at Union High, I sincerely hope that you enjoy the new additions to our lobby. Hopefully, they will make our free periods a lot more relaxing. If you happen to have one of the same free periods as I do, then please challenge me to a game of pool!

In paragraph 4, the word they refers to  _______ .

 Choose the word or phrase among A, B, C or D that best fits the blank space in the following passage:

"Nowadays people are more aware that wildlife all over the world is in (1)….  . Many species of animals are threatened, and could easily become (2)….   if we do not make an effort to (3)….. them. There are many reasons for this. In some cases, animals are (4)….. for their fur or for other valuable parts of their bodies. Some birds, such as parrots, are caught (5)…. , and sold as pets. For many animals and birds, the problem is that their habitats - the place where they live - is (6)…. . More (7)….  is used for farms, for houses and industry, and there are fewer open spaces than there once were. Farmers use powerful Chemicals to help them grow better (8)…. , but these Chemicals pollute the environment and (9)… wildlife. The most successful animals on Earth, human beings, will soon be the only ones (10)….. unless we can solve this problem."

9. but these Chemicals pollute the environment and (9)… wildlife. 

Chọn từ thích hợp điền vào chỗ trống:

THE THREAT TO THE ENVIRONMENT

Nowadays people are more aware that wildlife all over the world is in danger. Many (1)________of animals are threatened, and could easily become (2)______ if we do not make an effort to protect them. There are many (3)_______ for this. In some cases, animals are hunted for their fur or for othervaluable parts of their bodies. Some birds, such as parrots, are caught (4)________and sold as pets. For many animals and birds, the problem is that their habitat - the (5)________where they live - is disappearing. More (6)________is used for farms, for houses or industry, and there are fewer open (7)________than there once were. Farmers use powerful chemicals to help them grow better (8)________, but these chemicals pollute the environment and (9)________wildlife. The most successful animals on earth - human beings - will soon be the only Ones left, unless we can (10)________this problem.

(7)________

Culture is a word in common use with complex meanings, and is derived, like the term broadcasting, from the treatment and care of the soil and of what grows on it. It is directly related to cultivation and the adjectives cultural and cultured are part of the same verbal complex. A person of culture has identifiable attributes, among them are knowledge of and interest in the arts, literature, and music. Yet the word culture does not refer solely to such knowledge and interest nor, indeed, to education. At least from the 19th century onwards, under the influence of anthropologists and sociologists, the word culture means has come to be used generally both in the singular and the plural (cultures) to refer to a whole way of life of people, including their customs, laws, conventions, and values.
Distinctions have consequently been drawn between primitive and advanced culture and cultures, between elite and popular culture, between popular and mass culture, and most recently between national and global cultures. Distinctions have been drawn too between culture and civilization; the latter is a word derived not, like culture or agriculture, from the soil, but from the city.The two words are sometimes treated as synonymous. Yet this is misleading. While civilization and barbarism are pitted against each other in what seems to be a perpetual behavioural pattern, the use of the word culture has been strongly influenced by conceptions of evolution in the 19th century and of development in the 20th century. Cultures evolve or develop. They are not static. They have twists and turns. Styles change. So do fashions. There are cultural processes. What, for example, the word cultured has changed substantially since the study of classical (that is, Greek and Roman) literature, philosophy, and history ceased in the 20th century to be central to school and university education. No single alternative focus emerged, although with computers has come electronic culture, affecting kinds of study, and most recently digital culture. As cultures express themselves in new forms not everything gets better or more civilized.
The multiplicity of meanings attached to the word made and will make it difficult to define. There is no single, unprobfematic definition, although many attempts have been made to establish one. The only non-problematic definitions go back to agricultural meaning (for example cereal culture or strawberry culture) and medical meaning (for example, bacterial culture or penicillin culture). Since in anthropology and sociology we also acknowledge culture clashes, culture shock and counter- culture, the range of reference is extremely wide

Which of the following is NOT stated in the passage?

Choose the best answer to complete the passage.

LEARNING HOW TO LEARN AND THINK

What is the point of the education system? Although this question may seem ridiculous at first (1) ____, it is actually not stupid as it sounds. The reason it is (2) ____ trying to answer is that schools and university clearly (3) ____ academic achievement, passing exams and gaining (4) ____ much more than acquiring skills such as (5) ____ children or car maintenance. But why is it? Why do they neglect to teach (6) ____ skills at school?

One answer may be that schools don't (7) ____ to help us gain useful knowledge about the world. At school, what we are (8) ____ learning is how to learn effectively. The idea is that we can then (9) ____ use of that ability later on in life when we come to deal (10) ____ more practical aspects of day- to-day living.

However, some people argue that the (11) ____ system is in fact a failure because it doesn't actually teach children how to become good thinkers. Learning how to learn is one thing. Learning how to learn is one thing. Learning how to think is (12) ____ another.

(10) ____

Choose the letter A, B, C or D to answer these following questions:
   Dinosaurs were reptiles that lived during a period of earth’s history called the Mesozoic Era, which is also known as the Age of Reptiles. The first dinosaurs appeared more than 200 million years ago. For many millions of years, they dominated the land with their huge size and strength. Then about 65 million years ago, they died out rather suddenly, never to re-emerge. The word “dinosauras” comes from two Greek words meaning “terrible lizard”. Dinosaurs were not lizards, but their appearance could be truly terrifying. The biggest ones weighed more than ten times as much as a mature elephant and nearly equalled the size of most modern-day whales. The famous kinds of dinosaurs, including the brontosaur and tyrannosaurus rex, reached 80 to 90 feet in length. Not all dinosaurs were giant, however, some were actually not larger than a chicken. Scientists still do not know what caused dinosaurs to disappear. One theory involves a change of the earth’s climate. It is believed that temperatures dropped significantly towards the end of the Cretaceous protection, it is possible that the climate became too chilly for dinosaurs. In contrast, other species having protection, such as the mammals and birds, were able to survive.

What is the best title for this passage?

Choose the best answer:
After more than fifty years of television, it might seem only obvious to conclude that it is here to (1) ______ . There have been many objections to it during this time, of course, and (2) ______ a variety of grounds. Did it cause eye-strain? Was the (3) ______ bombarding us with radioactivity? Did the advertisements contain subliminal messages, persuading us to buy more? Did children turn to violence through watching it, either because so (4) ______ programmes taught them how to shoot, rob, and kill, or because they had to do something to counteract the hours they had spent glued to the tiny screen? Or did it simply create a vast passive (5) ______ drugged by glamorous serials and inane situation (6) ______ ? On the other hand did it increase anxiety by sensationalizing the news [or the news which was (7) ______ by suitable pictures] and filling our living rooms with war, famine and political unrest? (8) ______ in all, television proved to be the all-purpose scapegoat for the second half of the century, blamed for everything, but above all, eagerly watched. For no (9) ______ how much we despised it, feared it, were bored by it, or felt that it took us away from the old paradise of family conversation and hobbies such as collecting stamps, we never turned it off. We kept staring at the screen, aware that our own tiny (10) ______ was in if we looked carefully.
3.:

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:
    Animation traditionally is done by hand-drawing or painting successive frame of an object, each slightly different than the proceeding frame. In computer animation, although the computer may be the one to draw the different frames, in most cases the artist will draw the beginning and ending frames and the computer will produce the drawings between the first and the last drawing. This is generally referred to as computer-assisted animation, because the computer is more of a helper than an originator. 
    In full computer animation, complex mathematical formulas are used to produce the final sequences of pictures. These formulas operate on extensive databases of numbers that defines the objects in the pictures as they exist in mathematical space. The database consists of endpoints, and color and intensity information. Highly trained professionals are needed to produce such effects because animation that obtains high degrees of realism involves computer techniques from three-dimensional transformation, shading, and curvatures.
    High-tech computer animation for film involves very expensive computer systems along with special color terminals or frame buffers. The frame buffer is nothing more than a giant image memory for viewing a single frame. It temporarily holds the image for display on the screen.
    A camera can be used to film directly from the computer’s display screen, but for the highest quality images possible, expensive film recorders are used. The computer computers the positions and colors for the figures in the picture, and sends this information to the recorder, which captures it on film. Sometimes, however, the images are stored on a large magnetic disk before being sent to the recorder. Once this process is completed, it is replaced for the next frame. When the entire sequence has been recorded on the film, the film must be developed before the animation can be viewed. If the entire sequence does not seem right, the motions must be corrected, recomputed, redisplayed, and rerecorded. This approach can be very expensive and time – consuming. Often, computer-animation companies first do motion tests with simple computer-generated line drawings before selling their computers to the task of calculating the high-resolution, realistic-looking images.

Which of the following statement is supported by the passage?

Choose the best answer to complete the passage.

Most people (1) ____ learning with formal education at school, college, university etc. We are all told, from an early age, that we should get a good education'. Generally speaking, it is true that a formal education and the resulting qualifications are important. Education may (2) ____ our potential to find better, more satisfying jobs, earn more and perhaps, become more successful in our chosen career.

However, 'schooling' is only one type of learning. There are many other opportunities to further your (3) ____ and develop the skills you need throughout life. Knowledge can be acquired and skill sets developed anywhere - learning is unavoidable and happens all the (4) ____. However, lifelong learning is about creating and maintaining a positive attitude to learning both for personal and professional development.

Lifelong learners are self-motivated to learn and develop because they want to. (5) ____ learning can enhance our understanding of the world around us, provide us with more and better opportunities and improve our quality of life. People learn for personal development and for professional (6) ____. There are many reasons why people learn for personal development. You may want to increase your knowledge or (7) ____ around a particular hobby or pastime that you enjoy. Perhaps you want to develop some entirely new skill that will in some way enhance your life – take a pottery (8) ____ car mechanic course for example. Perhaps you want to research a medical condition or your ancestry.

If you do find yourself unemployed, then use the time wisely. Learning something new can pay off with new opportunities which might not otherwise have (9) ____. While you are employed, take advantage of training, coaching or mentoring opportunities and work on your continuous professional development as you will likely (10) ____ better at what you do and more indispensable to your current or future employer.

(5) ____

Read the following passage and mark the letter A. B. C or D your answer sheet to indicate the correct answer to each of the questions.

CAN ANIMALS TALK?

In 1977, a young Harvard graduate named Irene Pepperberg brought a one-year-old African gray parrot into her lab, and attempted something very unusual. At a time when her fellow scientists thought that animals could only communicate on a very basic level, Irene set out to discover what was on a creature's mind by talking to it. The bird, named Alex, proved to be a very good pupil.

Scientists at the time believed that animals were incapable of any thought. They believed that animals only reacted to things because they were programmed by nature to react that way, not because they had the ability to think or feel. Any pet owner would probably disagree. Pepperberg disagreed, too, and started her work with Alex to prove them wrong.

Pepperberg bought Alex in a pet store. She let the store's assistant pick him out because she didn't want other scientists saying later that she'd deliberately chosen an especially smart bird for her work. Most researchers thought that Pepperberg's attempt to communicate with Alex would end in failure.

However, Pepperberg's experiment did not fail. In fact, over the next few years, Alex learned to imitate almost one hundred and fifty English words, and was even able to reason and use those words on a basic level to communicate. For example, when Alex was shown an object and was asked about its shape, color, or material, he could label it correctly. He could understand that a key was a key no matter what its size or color, and could figure out how the key was different from others.

Pepperberg was careful not to exaggerate Alex's success and abilities. She did not claim that Alex could actually “use” language. Instead, she said that Alex had learned to use a two-way communication code. Alex seemed to understand the turn-taking pattern of communication.

According to the reading, other scientists believed that animals ________.

Exercise 1: Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

   The American type of football was developed in the 19th century from soccer and rugby football. Played by professionals, amateurs, college and high school students, or young children, football in American is one of the most popular sports besides basketball and baseball. It attracts millions of fans each fall and people are very supportive of their favourite teams. The football playing field of today is rectangular in shape and measures 100 yards long and 53.5 yards wide. White lines are painted on the playing field to mark off the distances to the end zone. The games is divided into four quarters, each fifteen minutes long. The first two quarters are known as the first half. There is a rest period between two halves which usually last about fifteen minutes. Each team has eleven players. Each team has offensive players who play when the team has possession of the ball and defensive players who play when the other team has the possession of the ball. Because of the body contact players have during the game, helmets are worn to protect their head and face area, whereas pads are worn to protect the shoulders, arms, and legs. Also, there are officials carrying whistles and flags to make certain that the rules of the game are followed during the game. The football is made of leather and is brown in colour. It is shaped much like an oval and has white rings near each end of the football. These rings help the players see the ball when it is thrown or someone is running with it. The eight stitches on the top of the football help the players to grip the ball when throwing or passing. The most famous game of the year is Super Bowl that is played in January or February. It is televised around the world and is watched by millions of people each year.

As mentioned in the text, who are the most active when their team has the ball?

Read the passage and choose the best answer to compete each of the statements that follow
The hippopotamus is the third largest land animal, smaller only than the elephant and the rhinoceros. Its name comes from two Greek words which mean "river horse". The long name of this animal is often shortened to the easier to handle term "hippo."
The hippo has a natural affinity for the water. It does not float on top of the water; instead, it can easily walk along the bottom of a body of water. The hippo commonly remains underwater for three to five minutes and has been known to stay under for up to half an hour before coming up for air.
In spite of its name, the hippo has relatively little in common with the horse and instead has a number of interesting similarities in common with the whale. When a hippo comes up after a stay at the bottom of a lake or river, it releases air through a blowhole, just like a whale. In addition, the hippo resembles the whale in that they both have thick layers of blubber for protection and they are almost completely hairless.

The last line states that the hippo does not_____________

Culture is a word in common use with complex meanings, and is derived, like the term broadcasting, from the treatment and care of the soil and of what grows on it. It is directly related to cultivation and the adjectives cultural and cultured are part of the same verbal complex. A person of culture has identifiable attributes, among them are knowledge of and interest in the arts, literature, and music. Yet the word culture does not refer solely to such knowledge and interest nor, indeed, to education. At least from the 19th century onwards, under the influence of anthropologists and sociologists, the word culture means has come to be used generally both in the singular and the plural (cultures) to refer to a whole way of life of people, including their customs, laws, conventions, and values.
Distinctions have consequently been drawn between primitive and advanced culture and cultures, between elite and popular culture, between popular and mass culture, and most recently between national and global cultures. Distinctions have been drawn too between culture and civilization; the latter is a word derived not, like culture or agriculture, from the soil, but from the city.The two words are sometimes treated as synonymous. Yet this is misleading. While civilization and barbarism are pitted against each other in what seems to be a perpetual behavioural pattern, the use of the word culture has been strongly influenced by conceptions of evolution in the 19th century and of development in the 20th century. Cultures evolve or develop. They are not static. They have twists and turns. Styles change. So do fashions. There are cultural processes. What, for example, the word cultured has changed substantially since the study of classical (that is, Greek and Roman) literature, philosophy, and history ceased in the 20th century to be central to school and university education. No single alternative focus emerged, although with computers has come electronic culture, affecting kinds of study, and most recently digital culture. As cultures express themselves in new forms not everything gets better or more civilized.
The multiplicity of meanings attached to the word made and will make it difficult to define. There is no single, unprobfematic definition, although many attempts have been made to establish one. The only non-problematic definitions go back to agricultural meaning (for example cereal culture or strawberry culture) and medical meaning (for example, bacterial culture or penicillin culture). Since in anthropology and sociology we also acknowledge culture clashes, culture shock and counter- culture, the range of reference is extremely wide

It is difficult to give the definitions of the word culture EXCEPT for its.................

It's often said that we learn things at the wrong time. University students frequently do the minimum of work because they're crazy about a good social life instead. Children often scream before their piano practice because it’s so boring. They have to be given gold stars and medals to be persuaded to swim, or have to be bribed to take exams. But the story is different when you’re older.

Over the years, I've done my share of adult learning. At 30, I went to a college and did courses in History and English. It was an amazing experience. For starters, I was paying, so there was no reason to be late - I was the one frowning and drumming my fingers if the tutor was late, not the other way round. Indeed, if I could persuade him to linger for an extra five minutes, it was a bonus, not a nuisance. I wasn't frightened to ask questions, and homework was a pleasure not a pain. When I passed an exam, I had passed it for me and me alone, not for my parents or my teachers. The satisfaction I got was entirely personal

Some people fear going back to school because they worry that their brains have got rusty. But the joy is that, although some parts have rusted up, your brain has learnt all kinds of other things since you were young. It has learnt to think independently and flexibly and is much better at relating one thing to another. What you lose in the rusty department, you gain in the maturity department.

In some ways, age is a positive plus. For instance, when you're older, you get less frustrated. Experience has told you that, if you're calm and simply do something carefully again and again, eventually you'll get the hang of it. The confidence you have in other areas - from being able to drive a car, perhaps - means that if you can’t, say, build a chair instantly, you don't, like a child, want to destroy your first pathetic attempts. Maturity tells you that you will, with application, eventually get there.

I hated piano lessons at school, but I was good at music. And coming back to it, with a teacher who could explain why certain exercises were useful and with musical concepts that, at the age of ten, I could never grasp, was magical. Initially, I did feel a bit strange, thumping out a piece that I'd played for my school exams, with just as little comprehension of what the composer intended as I'd had all those years before. But soon, complex emotions that I never knew poured out from my fingers, and suddenly I could understand why practice makes perfect.

It is implied in paragraph 1 that ...................

Đọc đoạn văn sau và chọn đáp án đúng cho mỗi câu hỏi:

Species that belong to an area are said to be native species. Typically, they have been part of a given biological landscape for a long period, and they are well adapted to the local environment and to the presence of other native species in the same general habitat. Exotic species are interlopers, foreign elements introduced intentionally or accidentally into new settings through human activities. In one context an introduced species may cause no obvious problems and may, over time, be regarded as being just as "natural" as any native species in the same habitat. In another context, exotics may seriously disrupt delicate ecological balances and create a cascade of unintended consequences. The worst of these unintended consequences arise when introduced species put native species in destruction by preying on them, altering their habitats, or out-competing them in the struggle for food resources. Although biological introductions have affected environments the world over, the most destructive, effects have occurred on islands, where introduced insects, cats, pigs, rats, mongooses, and other nonnative species have caused the grave endangerment or outright extinction of literally hundreds of species during the past 500 years. One of other reason to cause species extinction is overexploitation. This word refers to the utilization of a species at a rate that is likely to cause its extreme endangerment or outright extinction. Among many examples of severe overexploitation, the case of the great whales stands out in special relief. By the middle of the 20th century, unrestricted whaling had brought many species of whales to incredibly low population sizes. In response to public pressure, in 1982 a number of nations, including the USA, agreed to an international moratorium on whaling. As a direct result, some whale species which are thought to have been on extinction's doorstep 25 years ago have made amazing comebacks, such as grey whales in the western Pacific.  Others remain at great risk. Many other species, however, continue to suffer high rates of exploitation because of the trade in animal parts. Currently, the demand for animal parts is centered in several parts of Asia where there is a strong market for traditional medicines made from items like tiger bone and rhino horn.

Native species _______.  

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions:
The poaching crisis wiping out Africa's elephants is costing the continent's economies millions in lost tourism revenue, according to a new study. Researchers looked at visitor and elephant data across 25 countries, and modeled financial losses from fewer visitors in protected areas due to the illegal wildlife trade, which has caused elephant numbers to plummet by more than 100,000 in the last decade. (A)
The study team combined visitor numbers across 164 protected areas in 25 countries in forest and savannah elephants, and elephant population data from 2009 to 2013, to reach a “per elephant" value in terms of tourism income.
They concluded that Africa was most likely losing $26m in tourism revenue a year. (B) Around $9m of that is lost from tourists' direct spending, such as staying at hotels and buying crafts, with the rest through indirect value in the economy such as farmers and other suppliers supporting the tourist industry. 
The study, published in the journal Nature Communications, found that in most cases the revenue losses were higher than paying for stronger anti-poaching measures to keep elephant populations stable. (C) Dr. Robin Naidoo, the paper's lead author and , senior conservation wildlife scientist at WWF and his team found. In the case of central Africa's forest elephants, which are harder for tourists to see and therefore attract fewer visitors, the costs of protecting them exceed the benefits from tourism. Demand from south-east Asia has seen the price of ivory triple since 2009 and it is estimated that one elephant is killed every 15 minutes. (D) Corruption, a lack of resources, and, most importantly, increasingly sophisticated poachers have hamstrung African countries' efforts to stem the trade.
Naidoo said that the research was not suggesting economic issues should be the only consideration when protecting elephants, but framing the poaching crisis as a financial one could motivate African governments and communities.
“It gives an additional reason for some groups of people, who may not necessarily be motivated by intrinsic reasons for conversation, to engage with biodiversity conservation. It makes it clear to them that it's not just in the best interests of the world to conserve this stuff, but tangible reasons for a whole different group," he said.

The word sophisticated in paragraph 4 is closest in meaning to ____.