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 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.

(35) _____

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.

(27) _____

Choose the best answer

The World Wide Fund for Nature (WWF) is an international (1) ____ governmental organization for the (2) ____, research, and restoration of the environment. The organization was (3) ____ 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 (4) ____ worldwide, working in more (5) ____ 90 countries, supporting 100 conservation and environmental projects around the world. It is a charity, with (6) ____ 9% of its funding coming from voluntary, (7) ____ by private individuals and businesses.

The group says its mission is "to halt and reverse the (8) ____ 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 (9) ____ endangered species, pollution, and climate change. The organization (10) ____ more than 20 field projects worldwide. In the last few years, the organization set up offices and operations around the world.

(10) ____

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.

(8) ____

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.
Engineers have dreaming of an underwater link between Britain and France (35)_____1802. Finally in 1994 the Channel Tunnel ( nicknamed "The Chunnel" by the English) was (36)______ opened.
This fifteen billion dollar project took seven years to (37)_____. It is about 50 km long and built 45metres under the seabed .The trains which go through the Chunnel can travel at up 300 km/h due to the (38)_______electrical system.
The journey from London to Paris via the Chunnel takes just three hours. It is also (39)______ for drivers since they can load their cars onto the trains. They don't need to book in (40)______ , as trains (41)_______every few minutes. However, while on the train, there isn't much to do and many (42)_________ the Chunnel for this (43)________ the ferries , there is no duty-free shopping , no videogame parlou or refreshment stand (44)________can you look outside and enjoy the view . As a result, many would find the Chunnel unappealing and would take the ferry instead.
(40).......................................... 

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.

According to the second paragraph, by the middle of the 20th century ___.

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

"Do you want to take part in the battle to save the world’s wildlife? “Animal Watch” is a book which will (1)….. you in the fight for survival that (2)….  many of our endangered animals and show how they struggle on the (3)…. of extinction. As you enjoy the book’s 250 pages and over 150 coloured photographs, you will have the (4)…..  of knowing that part of your purchase money is being used to help animals (5)…. . From the comfort of your armchair, you will be able to observe the world’s animals close-up and explore their habitats. You will aỉso discover the terrible results of human greed for land, flesh and skins.
 “Animal Watch” is packed with fascinating facts. Did you know that polar bears cover their black noses (6)…. their paws so they can hunt their prey in the snow without being seen, for example? Or that for each orangutan which is captured, one has to die?
 This superb (7)…. has so (8)….. Britain’s leading wildlife charity that it has been chosen as Book of the Year, a (9)….. awarded to books which are considered to have made a major contribution to wildlife conservation. You will find “Animal Watch” at a special low introductory at all good bookshops, but hurry while (10)….. last."

1. “Animal Watch” is a book which will (1)….. you in the fight for survival 

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 motivate in paragraph 5 is closest in meaning to ____.

Very few people in the modern world obtain their food supply by hunting and gathering in the natural environment surrounding their homes. This method of harvesting from nature’s provision is the oldest known subsistence strategy and has been practised for at least the last two million years. It was, indeed, the only way to obtain food until rudimentary farming and the domestication of wild animals were introduced about 10,000 years ago.
Because hunter-gatherers have fared poorly in comparison with their agricultural cousins, their numbers have dwindled, and they have been forced to live in marginal environments, such as deserts and arctic wastelands. In higher latitudes, the shorter growing seasons have restricted the availability of plant life. Such conditions have caused a greater dependence on hunting, and on fishing along the coasts and waterways. The abundance of vegetation in the lower latitudes of the tropics, on the other hand, has provided a greater opportunity for gathering a variety of plants. In short, the environmental differences have restricted the diet and have limited possibilities for the development of subsistence societies.
Contemporary hunter-gatherers may help us understand our prehistoric ancestors. We know from the observation of modern hunter-gatherers in both Africa and Alaska that a society based on hunting and gathering must be very mobile. While the entire community camps in a central location, a smaller party harvests the food within a reasonable distancefrom the camp. When the food in the area has become exhausted, the community moves on to exploit another site. We also notice seasonal migration patterns evolving for most hunter-gatherers, along with a strict division of labor between the sexes. These patterns of behavior may be similar to those practised by mankind during the Paleolithic Period.

The word "conditions" in the second paragraph refers to ...................

Plants and animals will find it difficult to escape from or adjust to the effect of global warming, Scientists have already observerd shifts in the lifecycles of many plants and animals, such as flowers blooming earlier and birds hatching earlier in the spring. Many species have begun shifting where they live or their annual migration patterns due to warmer temperatures.
With further warming, animals will tend to migrate toward the poles and up mountainsides toward higher elevations. Plants will also attempt to shift their ranges, seeking new areas as old habitats grow too warm. In many places, however, human development will prevent these shifts. Species that find cities or farmland blocking their way north or south may become extinct. Species living in unique ecosystems, such as those found in polar and mountantop regions, are especially at risk because migration to new habitats is not possible. For example, polar bears and marine mammals in the Arctic are already threatened by dwindling sea ice but have nowhere farther to go.
Projecting species extinction due to global warming is extremely difficult. Some scientists have estimated that 20 to 50 percent of species could be committed to extiction with 2 to 3 Celsius degrees of further warming. The rate of warming, not just the magnitude, is extremely important for plants and animals. Some species and even entire ecosystems, such as certain types of forest, many not be able to adjust quickly enough and may disappear.
Ocean ecosystems, especially fragile ones like coral reefs, will also be affected by global warming. Warmer ocean temperatures can cause coral to "bleach", a state which if prolonged will lead to the death of the coral. Scientists estimate that even 1 Celsius degree of additional warming could lead to widespread bleaching and death of coral reefs around the world. Also increasing carbon dioxide in the atmosphere enters the ocean and increases the acidity of ocean waters. This acidification furter stresses ocean ecosystems.

The word “fragile” in paragraph 4 most probably means....................

Very few people in the modern world obtain their food supply by hunting and gathering in the natural environment surrounding their homes. This method of harvesting from nature’s provision is the oldest known subsistence strategy and has been practised for at least the last two million years. It was, indeed, the only way to obtain food until rudimentary farming and the domestication of wild animals were introduced about 10,000 years ago.
Because hunter-gatherers have fared poorly in comparison with their agricultural cousins, their numbers have dwindled, and they have been forced to live in marginal environments, such as deserts and arctic wastelands. In higher latitudes, the shorter growing seasons have restricted the availability of plant life. Such conditions have caused a greater dependence on hunting, and on fishing along the coasts and waterways. The abundance of vegetation in the lower latitudes of the tropics, on the other hand, has provided a greater opportunity for gathering a variety of plants. In short, the environmental differences have restricted the diet and have limited possibilities for the development of subsistence societies.
Contemporary hunter-gatherers may help us understand our prehistoric ancestors. We know from the observation of modern hunter-gatherers in both Africa and Alaska that a society based on hunting and gathering must be very mobile. While the entire community camps in a central location, a smaller party harvests the food within a reasonable distancefrom the camp. When the food in the area has become exhausted, the community moves on to exploit another site. We also notice seasonal migration patterns evolving for most hunter-gatherers, along with a strict division of labor between the sexes. These patterns of behavior may be similar to those practised by mankind during the Paleolithic Period.

A  typical  feature  of  both  modern  and  prehistoric  hunter-gatherers  is   that...................

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.

The word “inane” in paragraph 3 is closest in meaning to ______.

Choose the letter A, B, C or D to answer these following questions

   In developing countries, people are sometimes unaware of the importance of education, and there is economic pressure from those parents who prioritize their children's, making money in the short term over any long-term benefits of education. Recent studies on child labor and, poverty have suggested that when poor families reach a certain economic threshold where families are able to provide for their basic needs, parents return their children to school. This has been found to be true, once the threshold has been breached, even if the potential economic value of the children's work has increased since their return to school. Other problems are that teachers are often paid less than other professions; a lack of good universities and a low acceptance rate for good universities are evident in countries with a relatively high population density. India has launched EDUSAT, an education satellite that can reach remote parts of the country at a greatly reduced cost. There is also ail initiative supported by several major corporations to develop a $100 laptop. The laptops have been available since 2007. The laptops, sold at cost, will enable developing countries to give their children a digital education. In Africa, an "e-school program" has been launched to provide all 600,000 primary and high schools with computer equipment, learning materials and internet access within 10 years. Volunteer groups are working to give more individuals opportunity to receive education in developing countries through such programs as the Perpetual Education Fund. An International Development Agency project started with the support of American President Bill Clinton uses the Internet to allow co-operation by individuals on issues of social development.

According to recent studies, when parents are able to overcome their financial difficulty, ________.

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.

Why are there white rings on each end of the football?

Plants and animals will find it difficult to escape from or adjust to the effect of global warming, Scientists have already observerd shifts in the lifecycles of many plants and animals, such as flowers blooming earlier and birds hatching earlier in the spring. Many species have begun shifting where they live or their annual migration patterns due to warmer temperatures.
With further warming, animals will tend to migrate toward the poles and up mountainsides toward higher elevations. Plants will also attempt to shift their ranges, seeking new areas as old habitats grow too warm. In many places, however, human development will prevent these shifts. Species that find cities or farmland blocking their way north or south may become extinct. Species living in unique ecosystems, such as those found in polar and mountantop regions, are especially at risk because migration to new habitats is not possible. For example, polar bears and marine mammals in the Arctic are already threatened by dwindling sea ice but have nowhere farther to go.
Projecting species extinction due to global warming is extremely difficult. Some scientists have estimated that 20 to 50 percent of species could be committed to extiction with 2 to 3 Celsius degrees of further warming. The rate of warming, not just the magnitude, is extremely important for plants and animals. Some species and even entire ecosystems, such as certain types of forest, many not be able to adjust quickly enough and may disappear.
Ocean ecosystems, especially fragile ones like coral reefs, will also be affected by global warming. Warmer ocean temperatures can cause coral to "bleach", a state which if prolonged will lead to the death of the coral. Scientists estimate that even 1 Celsius degree of additional warming could lead to widespread bleaching and death of coral reefs around the world. Also increasing carbon dioxide in the atmosphere enters the ocean and increases the acidity of ocean waters. This acidification furter stresses ocean ecosystems.

The level of acidity in the ocean is increased by......................

Very few people in the modern world obtain their food supply by hunting and gathering in the natural environment surrounding their homes. This method of harvesting from nature’s provision is the oldest known subsistence strategy and has been practised for at least the last two million years. It was, indeed, the only way to obtain food until rudimentary farming and the domestication of wild animals were introduced about 10,000 years ago.
Because hunter-gatherers have fared poorly in comparison with their agricultural cousins, their numbers have dwindled, and they have been forced to live in marginal environments, such as deserts and arctic wastelands. In higher latitudes, the shorter growing seasons have restricted the availability of plant life. Such conditions have caused a greater dependence on hunting, and on fishing along the coasts and waterways. The abundance of vegetation in the lower latitudes of the tropics, on the other hand, has provided a greater opportunity for gathering a variety of plants. In short, the environmental differences have restricted the diet and have limited possibilities for the development of subsistence societies.
Contemporary hunter-gatherers may help us understand our prehistoric ancestors. We know from the observation of modern hunter-gatherers in both Africa and Alaska that a society based on hunting and gathering must be very mobile. While the entire community camps in a central location, a smaller party harvests the food within a reasonable distancefrom the camp. When the food in the area has become exhausted, the community moves on to exploit another site. We also notice seasonal migration patterns evolving for most hunter-gatherers, along with a strict division of labor between the sexes. These patterns of behavior may be similar to those practised by mankind during the Paleolithic Period.

According to the passage, subsistence societies depend mainly on................

Choose the letter A, B, C or D to complete the passage below

An endangered species is an animal or plant that's considered at …..(1)… of extinction. A species can be listed as endangered at the state, federal, and international level. On the federal level, the endangered species list is managed …..(2)…. the Endangered Species Act.

The Endangered Species Act (ESA) was ….. (3)…. by Congress in 1973. Under the ESA, the federal government has the responsibility to protect endangered species (species that are likely to become extinct throughout all or a large portion of their range), threatened species (species that are likely to become endangered in the near future), and critical habitat (areas vital to the survival of endangered or threatened species).

The Endangered Species Act has lists of protected plant and animal species….(4)….. nationally and worldwide. When a species is given ESA protection, it is said to be a "listed" species. Many additional species are evaluated for possible protection under the ESA, and they …..(5)…called “candidate” species.

(3) ..............

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.

The word "them" in paragraph 2 refers to ________.

The Sun today is a yellow dwarf star. It is fueled by thermonuclear reactions near its center that convert hydrogen to helium. The Sun has existed in its present state for about four billion six hundred million years and is thousands of times larger than the Earth.
By studying other stars, astronomers can predict what the rest of the Sun's life will be like.
About five billion years from now, the core of the Sun will shrink and become hotter. The surface temperature will fall. The higher temperature of the center will increase the rate of thermonuclear reactions. The outer regions of the Sun will expand approximately 35 million miles, about the distance to Mercury, which is the closest planet to the Sun. The Sun will then be a red giant star. Temperatures on the Earth will become too high for life to exist.
Once the Sun has used up its thermonuclear energy as a red giant, it will begin to shrink. After it shrinks to the size of the Earth, it will become a white dwarf star. The Sun may throw off huge amounts of gases in violent eruptions called nova explosions as it changes from a red giant to a white dwarf.
After billions of years as a white dwarf, the Sun will have used up all its fuel and will have lost its heat. Such a star is called a black dwarf. After the Sun has become a black dwarf, the Earth will be dark and cold. If any atmosphere remains there, it will have frozen over the Earth’s surface.

The passage has probably been taken from ..................

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. 
     How might volunteering contribute to lower blood pressure? Performing volunteer work could increase physical activity among people who aren’t otherwise very active, says lead study author Rodlescia Sneed, a doctoral candidate in social and health psychology at Carnegie Mellon University. It may also reduce stress. “Many people find volunteer work to be helpful with respect to stress reduction, and we know that stress is very strongly linked to health outcomes,” she says.
     As with any activity thought to improve health, researchers are trying to identify the specific characteristics of volunteering that provide the greatest benefit. For example, how much time would you need to put into volunteer work to lower your blood pressure or live longer? In the Carnegie Mellon study, 200 hours of volunteering per year correlated to lower blood pressure. Other studies have found a health benefit from as little as 100 hours of volunteering a year. Which types of volunteer activities improve health the most? No one really knows. Sneed speculates that mentally stimulating activities, like tutoring or reading, might be helpful for maintaining memory and thinking skills, while “activities that promote physical activity would be helpful with respect to cardiovascular health, but no studies have really explored this.”
     One key for deriving health benefits from volunteering is to do it for the right reasons. A 2012 study in the journal Health Psychology found that participants who volunteered with some regularity lived longer, but only if their intentions were truly altruistic. In other words, they had to be volunteering to help others—not to make themselves feel better.
      The Greek philosopher Aristotle once surmised that the essence of life is “To serve others and do good.” If recent research is any indication, serving others might also be the essence of good health.

What does the passage mainly discuss?