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:
Because writing has become so important in our culture, we sometimes think of it as more real than speech. A little thought, however, will show why speech is primary and writing secondary to language. Human beings have been writing at least 5,000 years, but they have been talking for much longer, doubtless ever since there have been human beings. When writing developed, it was derived from and represented speech, although imperfectly. Even today, there are spoken languages that have no written form. Furthermore, we all learn to talk well before we learn to write; any child who is not severely handicapped physically or mentally will learn to talk: a normal man cannot be prevented from doing so. On the other hand, it takes a special effort to learn to write; in the past, many intelligent and useful members of society did not acquire the skill, and even today many who speak languages with writing systems never learn to read or write while some who learn the rudiments of those skills do so imperfectly.
To affirm the primacy of speech over writing is not to disparage the later. One advantage writing has over speech is that it is more permanent and makes possible the records that any civilization must have. Thus, if speaking makes us human, writing makes us civilized.

The word “acquire” in the passage mostly means     .

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_____ the cold weather, we kept the fire burning all day.

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Scientists have uncovered a new threat to the world’s endangered coral reefs. They  have found that most are incapable of growing quickly enough to compensate for rising sea levels triggered by global warming. The study suggests that reefs – which are already suffering serious degradation because the world’s seas are warming and becoming more acidic – could also become overwhelmed by rising oceans.  The research – led by scientists at Exeter University and published in Nature this week – involved studying growth rates for more than 200 tropical western Atlantic and Indian Ocean reefs. It was found only 9% of these reefs had the ability to keep up with even the most optimistic rates of sea-level rises forecast by the Intergovernmental Panel on Climate Change. “For many reefs across the Caribbean and Indian Ocean regions, where the study focused, rates of growth are slowing due to coral reef degradation,” said Professor Chris Perry, of Exeter University. “Meanwhile, rates of sea-level rise are increasing – and our results suggest reefs will be unable to keep up. As a result, water depths above most reefs will increase rapidly through this century.”  Sea levels rose by several inches over the past century and measurements indicate the speed of this increase is now rising significantly. Two key factors are involved: climate change is making ocean water warmer and so it expands. And as ice sheets and glaciers melt, they increase amounts of water in the oceans.  At the same time, reefs are being weakened by ocean warming and also by ocean acidification, triggered as the seas absorb more and more carbon dioxide. These effects lead to bleaching events that kill off vast stretches of coral and limits their ability to grow.  “Our predictions, even under the best case scenarios, suggest that by 2100, the inundation of reefs will expose coastal communities to significant threats of shoreline change,” said co-author Prof Peter Mumby of Queensland University. This point was backed by US marine scientist Ilsa Kuffner writing in a separate comment piece for Nature. “The implications of the study are dire. Many island nations and territories are set to quickly lose crucial natural resources.” 
6. The word “inundation” is closest in meaning to _____________

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The majority of Americans can live comfortable lives on the salaries they earn, without the support of a universal public-welfare system. These so-called middle-class Americans generally own their own homes and cars, spend some time each year on vacation, and can pay – at least in part - for a college education for their children. Most Americans set (1) _______ money in savings accounts to help pay major expenses; many invest in the stock market in hopes of earning a healthy return on their investments.  Most buy insurance, especially life and medical insurance, frequently with contributions (2) _____ the companies for which they work. Many companies also have retirement plans which they and their employees put aside money for their retirement pensions. When added to Social Security payments, pensions (3) _______ many tired Americans to live comfortably. On the other hand, for older Americans who require longterm care outside of a hospital, a nursing home can be very expensive. In 1993, a family of four with a yearly income of $14,763 or less was considered poor by American standards; 15.1 percent of American families fell into this category. In addition to the benefits discussed above, many families below the (4) ________line receive welfare payments, sums of money provided by the government each month to those whose income is too low to obtain such necessities as food, clothing and shelter. The most common form of welfare payment has been through a program called Aid to Families With Dependent Children (AFDC). Originally (5) _______to help children whose fathers had died, AFDC evolved into the main source of regular income for millions of poor American families

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There is substantial evidence that students going off to college have changed over the years. For one thing, studies show that they are emotionally closer to their parents and their parents to them. One thing that means is that they depend on each other more for happiness. It puts a burden on children for parents to use their children as vehicles for their own happiness - although today’s young people seem complicit in this arrangement, perhaps because they have known no other way even if it creates anxiety in the children. That’s one reason parents like to be involved in their children’s college experiences, and colleges have had to devise novel ways of getting parents off campus when they transport their kids to school.
There’s also evidence that students today seem to be choosing schools with reference to proximity to home. The closer a student is to home, the easier it is to bring the laundry home and to land in your old bed with tea and sympathy when you have the sniffles. And the easier it is for parents to visit you at university whenever the mood strikes. The amount of visiting parents do is far more than in generations past.
But in a real sense, students don’t really leave their parents behind. Their parents go to college right along with them - in their front pockets. That is, the parents are a speed dial away by cellphone. This, of course, significantly reduces independence. A student doesn’t get the chance to solve minor problems on his own
- he just calls Mom or Dad. A student has initial problems getting along with a roommate? A roommate doesn’t do laundry as often as the other roommate wishes? A student gets a C grade on her first paper? Instead of absorbing the negative information and figuring out how to resolve the problem or how to do better, the call gets made to home, where Mom or Dad solves the problem, often by calling the school administration. This kind of behavior is, sadly, commonplace today and is a mark of the lack of coping skills among students because all the lumps and bumps have been taken out of life for them until now.
In addition to being tethered to parents, incoming freshmen are now very heavily connected by cellphone to classmates from high school, who are presumably at other colleges. So there isn’t the great impetus to mix and venture forth to meet new people, to get out of one’s comfort/one, to get drawn into new experiences, that has traditionally marked the beginning of freshman year. The laws of physics still apply, 6 and it is difficult to be meeting new people and seeking novel experiences while you are talking to your old pals.

The word “vehicles” in the first paragraph may be replaced by    .

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"Did you see that?" Joe said to his friend Bill. "You're a great shooter!"
Bill caught the basketball and bounced it before throwing it again. The ball flew into the net. "Bill, you never miss!" Joe said admiringly.
"Unless I'm in a real game," Bill complained. "Then I miss all the time."
Joe knew that Bill was right. Bill performed much better when he was having fun with Joe in the school yard than he did when he was playing for the school team in front of a large crowd.
"Maybe you just need to practice more," Joe suggested.
"But I practice all the time with you!" Bill objected. He shook his head. "I just can't play well when people are watching me."
"You play well when I'm watching," Joe pointed out.
"That's because I've known you since we were five years old," Bill said with a smile. "I'm just not comfortable playing when other people are around."
Joe nodded and understood, but he also had an idea.
The next day Joe and Bill met in the school yard again to practice. After a few minutes, Joe excused himself.
"Practice without me," Joe said to his friend. "I'll be back in a minute."
Joe hurried through the school building, gathering together whomever he could find - two students, a math teacher, two secretaries, and a janitor. When Joe explained why he needed them, everyone was happy to help.
Joe reminded the group to stay quiet as they all went toward the school's basketball court. As Joe had hoped, Bill was still practicing basketball. He made five baskets in a row without noticing the silent people standing behind him.
"Hey, Bill!" Joe called out finally.
Bill turned. A look of surprise came over his face.
I just wanted to show you that you could play well with people watching you," Joe said. "Now you'll have nothing to worry about for the next game!"

In line 6, the word performed is closest in meaning to      

Each sentence has a mistake. Findit by chosing A B C or D

A smile can be observed, described, and reliably indentify; it can also be elicited and manipulated under experimental conditions

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In the USA, the UK and many other countries, a lot of babies were born in the “baby boom” of the late 1940s and 1950s; after that the birth-rate fell. Baby boomers have now retired, or are approaching retirement, and this is causing headaches for many organizations: there are not enough people to succeed their top managers when they retire.
Does your organization have key staff who can’t easily be replaced? A CEO or financial director, perhaps, or a technical expert with knowledge that nobody else in the organization has. If your answer is “yes”, what will happen when they retire, or leave for another company? Will you wait until the last moment before looking for someone to replace them? Or is your organization thinking about likely future changes now, as it should be, and making plans, so that there is likely to be someone ready to replace the person leaving? If the answer is that you are planning ahead, your organization is carrying out succession planning.
Succession planning means looking inside the organization for “high-fliers” - current staff members with the potential to fill key positions - and planning the training, responsibilities and promotion they need, to make them ready when a senior vacancy occurs - which may not be for several years. The company benefits by being able to make an internal promotion when a key person leaves, and in the meantime it benefits by developing the skills of its high-fliers and encouraging them to stay. And the high-fliers benefit, because they achieve their full potential, a career is planned for them within the organization, and they can look forward to a senior post in time.
The training program planned for the high-fliers will help them to develop the leadership skills they need for more senior roles, skills such as planning long-term strategies. A career path is also planned, so that each high-flier moves into a number of different positions over a few years, to gain the experience and know ledge they need.
Sometimes a staff member is chosen as a potential successor to a particular senior manager, but a better method is for organizations to select a number of high-fliers, and prepare them for a range of senior roles. An organization can’t be certain when a particular senior manager will leave. Having a group of people being prepared fee top positions makes it easier to replace someone who leaves unexpectedly, and also means that there are other people available if a high-flier leaves the company.

What does the word “them” in the 3rd paragraph refer to?

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Anna Gomez is a successful TV sports presenter, but most people still think of her as the famous women’s ice-skating champion who won several important competitions when she was younger. “As a child, my dream was actually to become a ballet dancer – I didn’t own any skates until I was nine, and didn’t become really keen on skating until I was fourteen,” says Anna. She went on to university, where, despite ice-skating almost all the time, she left with an excellent degree. “I felt I owed it to my parents. They supported me through university, and expected me to do well there – I didn’t feel I could disappoint them.” In a sport where most stars become famous as teenagers, Anna was unusual in being in her twenties before she won any major titles. “When I was younger, I got very angry at competitions, shouting at judges if I disagreed with them. That made me unpopular, especially with other skaters. My technique was just as good as theirs and I had a very encouraging coach at the time. The problem was in my head – I just didn’t think I had what it takes to be a champion. That changed as I won more competitions, and I was performing at my best by the age of twenty-five.” Anna retired from professional ice-skating five years later, having accomplished great success during that period. “It was a difficult decision. As you get near the end of your career, people always ask when you’re going to stop. At the time, I wasn’t sure that I was actually ready to give up. But, looking back, I’m glad I stopped when I did. You shouldn’t think too much about the past – just move on to the next thing.”  
1. What is the writer doing in the text?

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Until the twentieth century cigarettes were not an important threat to public health. Men used tobacco mainly in the form of cigars. They chewed tobacco, piped tobacco, and snuffed. Most women did not use tobacco at all. The cigarette industry began in 1870s with the development of the cigarette manufacturing machine. This made it possible to produce great numbers of cigarettes very quickly, and it reduced the price. Today cigarette smoking is a widespread habit. About forty-three percent of the adult men and thirty-one percent of the adult women in the United States smoke cigarettes regularly. It is encouraging to note, however, that millions of people have quits smoking. Seventy-five percent of the male population and forty-six percent of the female population have smoked cigarettes for some time during their lives, but twenty-six percent of these men and eleven percent of women have stopped smoking. The number of persons who have given up smoking is increasing. Men as a group smoke more than women. Among both men and women the age group with the highest proportion of smokers is the age group 24-44. Income, education, and occupation all play a part in determining a person’s smoking habit. City people smoke more than people living on farms. Well-educated men with high incomes are less likely to smoke cigarettes than men with fewer years of schooling and lower incomes. On the other hand, if a well-educated man with a higher income smokes, he’s likely to smoke more packs of cigarettes per day. The situation is somewhat different for women. There are slightly more smokers among women with higher family incomes and higher education than among the lower income and lower educational groups. These more highly educated women tend to smoke more heavily. Among teenagers the picture is similar. There are fewer teenager smokers from upper-income, well-educated families, and also fewer from families living in farm areas. High school students who are preparing for college are less likely to smoke than those who don’t plan to continue their education after high school. Children are most likely to start smoking if one or both of their parents smoke  
3. The following factors will be likely to decide whether a person smokes EXCEPT ______

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(Line 1) Horace Pippin, as an African-American soldier during World War I, was wounded in his right arm. He discovered, however, that by keeping his right wrist steady with his left hand, he could paint and draw. Pippin was not trained, but his artistic sensitivity and intuitive feel for two- dimensional design and the arrangement of colour and patterns made him one of the finest Primitive artists America has produced.
(Line 6) Pippin did a series of paintings on the abolitionist John Brown and one on his war experiences, but he shied away from social issues for the most part and achieved his greatest success with scenes of the people and places of his hometown of West Chester, Pennsylvania. His Domino Players, featuring four women gathered around a wooden table in a simple kitchen setting, is an excellent example of his rural domestic scenes.

Where in the passage is the name of Pippin’s hometown mentioned?

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While many behaviors and practices associated with going green are designed to save  money, there are certain ways in which green living can actually be moderately to very expensive. Much of the technology associated with green living (1) ____________ provide benefits to the environment but often at a much higher cost than their traditional counterparts. For instance, the use of solar panels can potentially save you money on your energy bills, but they can (2) ______________ thousands of dollars to install. Energy-efficient appliances are designed to use less electricity and water but they often come with a high price tag.  Going green can also potentially have a negative effect on the environment. For (3) __________, the development of alternative fuels is an innovation in the green movement in an effort to reduce reliance on (4) ___________ natural resources. While these fuels are intended to reduce the toxic emissions caused by the burning of traditional gasoline, they may have unintentionally caused the opposite effect. One of these alternative fuels, E85, actually (5) ___________ more ozone into the atmosphere than traditional fuel. While ozone is a natural part of the Earth’s upper atmosphere, if it becomes concentrated in the lower atmosphere, it can potentially increase air pollution in areas where smog is a concern, which can in turn impact the health of those living in these areas

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 following questions:
We have all had bad experiences with restaurants, stores, or hotels. Maybe you have gone to a restaurant that served terrible food. Perhaps you have gone to a store that had high prices or bad service. Or maybe you have booked a hotel and found out later that the room was nothing like the advertisement.
These days, we have a better chance of preventing these unpleasant surprises. We can do this by using apps. “App” is short for “application”. An app is a computer programme on a smartphone. You can use apps to do almost anything. Apps can help you play games, get directions, talk to friends, and so on.
If f you want to find information about a store or a hotel, you can use a review app. Review apps help us evaluate services and products before we hand over our money. The idea is very simple. After you go to a restaurant or stay in a hotel, you can post a review with one of your apps. You can say anything you want. If you like a hotel you stayed in, you can tell people that it was wonderful. If you think that the food in a certain restaurant was bad, then you tell people not to eat there. Other people can use their apps to read your reviews.
Plenty of people prefer not to use these review apps. Many of these people prefer to go out and decide for themselves whether or not a service is good. However, review apps are getting more and more popular every day. Some apps are for specific services. For example, Tripadvisor focuses on travel, and Goodreads focuses on books. There are also other, larger apps that provide information for just about every service that you can think of. 5

The word “it” in paragraph 3 refers to     .

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All plants rely on nutrients taken from the soil in order to survive. However, in areas where the soil does not contain enough (35)_____ nutrients, some plants have adapted to (36) _____ their diets from another source: living organisms. Though they are few in number, carnivorous plants are (37)_____ fascinating beings that ―eat‖ anything from one-celled organisms to insects in order to survive. They are commonly found in marshlands. Carnivorous plants feature one of several types of ―traps‖ to ensnare prey, which they consume to make up for nutrients that may be missing from the soil. While there are over 400 species of carnivorous plants in the world today, some are more (38)_____ than others. The most well-known of these plants are the snap traps, which include the Venus flytrap. Snap traps are easily identified by their leaves, which are separated into two lobes that have the ability to fold together. Inside the lobes, the surface is covered with tiny hairs that are (39) _____ to movement. When the plant‘s prey brushes against the hairs, it triggers a closing mechanism that rapidly brings the two lobes together, trapping the prey (40)_____ inside. The response of the traps is phenomenal (41)_____ speed: the time between triggering the hairs and snapping shut is less than a second. As the prey struggles inside the trap, it only triggers more hairs, causing the leaves to tighten their (42) _____. The plant then secrets liquid chemicals from special glands into the trap to dissolve the prey and absorb all of its nutrients. Besides the Venus flytrap, only one other type of snap trap exists today, (43)_____ to as the waterwheel plant. The two share a common ancestor and differ only in a few ways. For instance, the waterwheel is an aquatic plant, while the flytrap is exclusively terrestrial. In addition, the flytrap feeds primarily on arthropods like spiders, while the waterwheel lives (44)_____ simple invertebrates, like certain types of plankton

Each sentence has a mistake. Findit by chosing A B C or D

The United States is a highly developed and industrializing  society

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The ruined temples of Angkor are perhaps one of the most impressive Seven Wonders of the World. Located in modern day Cambodia near Lake Tonle Sap, the largest freshwater lake in Asia, Angkor was the seat of power for the Khmer Empire for the ninth to the fifteenth century. The ruins of Angkor are documented as some of the most impressive ones in the world, rivaling the pyramids of Giza in Egypt. Why this mighty civilization died out is a question that archaeologists are now only beginning to ponder. The answer, it turns out, may be linked with the availability of fresh water.
One possible explanation for the downfall of the Khmer Empire has to do with the inhabitant’s irrigation system. The temples and palaces of Angkor were constructed around a series of artificial reservoirs and canals which were annually flooded to capacity by the Mekong River. Once filled, they were used to irrigate the surrounding paddies and farmland during the course of the year. Farmers were completely dependent on the water for their crucial rice crop. Without consistent irrigation, the farmers would have been unable to maintain functional crop production.
Scientists speculate that toward the end of the Khmer Empire the hydraulic system of the reservoirs and canals broke down. The construction of hundreds of sandstone temples and palaces required an enormous amount of physical labor. In addition, as the capital of Khmer Empire, Angkor contained upwards of one hundred thousand people who resided in and around Angkor. In order to feed so many people, the local farmers were driven to grow food more quickly and more efficiently. After centuries of continual use, the irrigation system was pushed beyond its capacity. Soil erosion, nutrient depletion, and loss of water led to decrease in the food supply. With the less food available, the people of Angkor slowly began to migrate to other parts of Cambodia, thus leaving the marvelous city of Angkor to be swallowed by the jungle. Therefore, it is speculated that the Khmer Empire may have fallen victim to its own decrepit infrastructure.

According to the passage, Lake Tonle Sap in Cambodia     .

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The aviation industry, especially the commercial aviation sector, is constantly striving to improve both the way it works and its customer satisfaction. It has begun using artificial intelligence. Though AI in the aviation industry is still in the nascent stage, some progress has been made already as certain leading carriers invest in AI. To make a long story short, AI can redefine how the aviation industry goes about its work. In 2017, American Airlines conducted an app development competition with the goal of having an app developed for making baggage screening easier for passengers. The competition, named HackWars, was themed upon artificial intelligence, drones and augmented and virtual reality. The winner, known as “Team Avatar,” developed an app that would not only allow passengers determine their baggage size before arriving at the airport, but also prepay any potential baggage-related expenses. United Airlines is using Amazon’s Alexa to have certain common customer queries answered. In September 2017, United announced a collaboration with Alexa. The feature is known as the United skill. To get started, all passengers need to do is to  add the United skill to their Alexa app and then start asking questions. Alexa answers common queries correctly, such as the status of a flight by number, check-in requests and availability of Wi-Fi on a flight. The reviews so far have been mixed, which points to the fact that there is a learning curve, and it is still a long way to go before AI can fully handle customer assistance. Tracking progress is an enormous challenge that airlines will face. The first thing they need to do is to develop analytics that will help them develop and process accurate data. However, that in itself is a challenge. What kind of analytics will help? For example, customer satisfaction is going to be one of the most important factors in success. What kind of analytics will determine that airlines have been improving on customer satisfaction parameters? AI needs huge investments, and probably the biggest risk in this is smaller, especially budget airlines are going to miss out on reaping the benefits of AI fully. Does that mean that the performance of the smaller carriers will be impacted? That might not be the case, because we might be moving toward more acquisitions and mergers. Bigger airlines will have a massive appetite for acquiring smaller airlines with an eye on the market. It is not all gloom and doom though, because smaller airlines like Southwest have already shown some initiatives toward embracing AI. It is surprising that a sector as important as aviation has woken up to AI so late. As AI in aviation picks up its pace, there could probably be a few mergers, acquisitions or even closure of small airlines which will not be able to afford the investments. Now, AI seems the best option to take aviation to the next level.
2. The word “carriers” in paragraph 1 probably means ______

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Without regular supplies of some hormones our capacity to behave would be seriously impaired; without others we would soon die. Tiny amounts of some hormones can modify our moods and our action, our inclination to eat or drink, our aggressiveness or submissiveness, and our reproductive and parental behavior. And hormones do more than influence adult behavior; early in life they help to determine the development of bodily form and may even determine an individual’s behavioral capacities. Later in life the changing outputs of some endocrine glands and the body’s changing sensitivity to some hormones are essential aspects of the phenomena of aging. Communication within the body and the consequent integration of behavior were considered the exclusive province of the nervous system up to the beginning of the present century. The emergence of endocrinology as a separate discipline can probably be traced to the experiments of Bayliss and Starling on the hormone secretion. This substance is secreted from cells in the intestinal walls when food enters the stomach; it travels through the bloodstream and stimulates the pancreas to liberate pancreatic juice, which aids in digestion. By showing that special cells secrete chemical agents that are conveyed by the bloodstream and regulate distant target organs or tissues, Bayliss and Starling demonstrated that chemical integration can occur without participation of the nervous system. William Bayliss and Ernest Henry Starling, two British physiologists, discovered and introduced the word hormone. In 1979, The Bayliss and Starling Society was founded as a forum for research scientists with specific interest in the chemistry, physiology and function of central and autonomic peptides. The Society also offered the travelling fellowship award for members who wanted to attend national and international academic conferences. Sometimes, the Society help schools to organize science fairs for secondary students and give them incentives to fall for related subjects. The term “hormone” was first used with reference to secretion. Starling derived the term from the Greek hormone, meaning “to excited or set in motion.” The term “endocrine” was introduced shortly thereafter, “Endocrine” is used to refer to glands that secrete products into the bloodstream. The term “endocrine” contrasts with “exocrine” which is applied to glands that secrete their products through ducts to the site of action. Examples of exocrine glands are the tear glands, the sweat glands, and the pancreas, which secretes pancreatic juice through a duct into intestine. Exocrine glands are also called duct glands, while endocrine glands are called ductless.
1. Which of the following is NOT mentioned as an effect of hormones?

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He decided ____________ another language.

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The biological community changes again as one moves from the city to the suburbs. Around all cities is a biome called the "suburban forest". The trees of this forest are species that are favored by man, and most of them have been deliberately planted. Mammals such as rabbits, skunks, and opossums have moved in from the surrounding countryside. Raccoons have become experts at opening garbage cans, and in some places even deer wander suburban thoroughfares. Several species of squirrel get along nicely in suburbia, but usually only one species is predominant in any given suburb -fox squirrels in one place, red squirrels in another, gray squirrels in a third - for reasons that are little understood. The diversity of birds in the suburbs is great, and in the South, lizards thrive in gardens and even houses. Of course, insects are always present. There is an odd biological sameness in these suburban communities. True, the palms of Los Angeles are missing from the suburbs of Boston, and there are species of insects in Miami not found in Seattle. But over wide stretches of the United States, ecological conditions in suburban biomes vary much less than do those of natural biome. And unlike the natural biomes, the urban and suburban communities exist in spite of, not because of, the climate.

What does the author imply about the effect of climate in the suburban biome?

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Globally we use more energy than ever before, and the demand is rapidly growing. Economic expansion of emerging market economies, population growth and our increasing use of energy-consuming devices are among the most important contributing factors. About one-third of the radiation hitting Earth’s atmosphere is reflected back out into space by clouds, ice, snow, sand and other reflective surfaces. The other two-thirds is absorbed by the Earth’s surface and the atmosphere. As the land, oceans and atmosphere heat up, they re-emit energy as infrared thermal radiation, which passes through the atmosphere. Heat-trapping gases like carbon dioxide (CO2) absorb this infrared radiation and prevent it from dissipating into space, giving rise to what we know as the greenhouse effect. The accumulation of CO2 and other greenhouse gases in the atmosphere is the dominating driver of recent climate change. CO2 is estimated to be responsible for 64 % of man-made global warming. Other greenhouse gases are released in much smaller amounts but still contribute significantly to the overall warming effect, as they are much more potent heat-trapping gases than CO2. The EU is taking action on many levels. One example is on fluorinated gases that are contributing less than CO2 but still a particular point of concern in addressing climate change. They are used in several types of products, such as in refrigeration, air-conditioning and heat pump equipment. While fluorinated gases are released into the atmosphere in smaller quantities than other greenhouse gases, they are extremely potent – they produce a warming effect 23 000 times greater than CO2. For this reason the EU has decided to control their use. The EU’s regulation on fluorinated greenhouse gases aims at cutting the Union’s emissions by two-thirds compared to 2014 levels. Chemicals are not only part of the problem – they are also part of the solution. Sustainable energy sources like solar power rely on chemical innovation using, for example, nanomaterials. One of the main challenges with renewable energy is how to increase its viability with the help of energy storage solutions. For example, solar panels have the best conditions in the desert, but that is not where most people live. Windmills also produce power during the night, which is when our energy consumption is at its lowest. In other words, technologies to improve energy storage and transportation is one of the important areas of research where innovation is needed  
3. According to paragraph 2, why does part of the energy received from the sun remain on Earth?