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.
(42).........................................

Reading to oneself is a modern activity which was almost unknown to the scholars of the classical and medieval worlds, while during the fifteenth century the term "reading" undoubtedly meant reading aloud. Only during thenineleenthcenturydid silent reading become commonplace.
One should be wary, however, of assuming that silent reading came about simply because reading aloud was a distraction to others. Examinations of factors related to the historical development of silent reading have revealed that it became the usual mode  of reading for most adults mainly because the tasks themselves changed in character.
The last century saw a steady gradual increase in literacy and thus in the number of readers. As the number of readers increased, the number of potential listeners declined and thus there was some reduction in the need to read aloud. As reading for the benefit of listeners grew less common, so came the flourishing of reading as a private activity in such public places as libraries, railway carriages and offices, where reading aloud would cause distraction to other readers.
Towards the end of the century, there was still considerable argument over whether books should be used for information or treated respectfully and over whether the reading of  materials such as newspapers was in some way mentally weakening. Indeed, this argument remains with us still in education. However, whatever its virtues, the old shared literacy  culture had gone and was replaced by the printed mass media on the one hand and by books and periodicals for a specialised readership on the other.
By the end of the twentieth century, students were being recommended to adopt attitudes to books and to use reading skills which were inappropriate, if not impossible, for the oral reader. The social, cultural and technological changes in the century had greatly altered what the term "reading" implied.

 The word "commonplace" in the first paragraph mostly means:

Overpopulation, the situation of having large numbers of people with too few resources and too little space, is closely associated with poverty. It can result from high population density, or from low amounts of resources, or from both. Excessively high population densities put stress on available resources. Only a certain number of people can be supported o a given area of land, and that number depends on how much food and other resources the land can provide. In countries where people live primarily by means of simple farming, gardening, herding, hunting, and gathering, even large areas of land can support only small numbers of people because these labor - intensive subsistence activities produce only small amounts of food.
In developed countries such as the United States, Japan and the countries of Western Europe, overpopulation generally is not considered a major cause of poverty. These countries produce large quantities of food through mechanized farming, which depends on commercial fertilizers, large - scale irrigation, and agricultural machinery. This form of production provides enough food to support the high densities of people in metropolitan areas.
A country's level of poverty can depend greatly on its mix of population density and agricultural productivity. Bangladesh, for example, has one of the world's highest population densities, with 1,147 persons per sq km. A large majority of the people of Bangladesh engage in low - productivity manual farming, which contributes to the country's extremely high level of poverty. Some of the smaller countries in Western Europe, such as the Netherlands and Belgium, have high population densities as well. These countries practice mechanized farming and are involved in high - tech indutries, however, are therefore have high standards of living.
At the other end of the spectrum, many countries in sub - Saharan Africa have population densities of less than 30 persons per sq km. Many people in these countries practice manual subsistence farming, these countries also have infertile land, and lack the economic resources and technology to boost productivity. As a consequence, these nations are very poor. The United States has both relatively low population density and high agricultural productivity; it is one of the world's weathiest nations.
High birth rates contribute to overpopulation in many developing countries. Children are assets to many poor families because they provide labor, usually for farming. Cultural norms in traditionally rural societies commonly sanction the value of large families. Also, the goverments of developing countries often provide little or no support, financial or political, for farming planning; even people who wish to keep their families small have difficulty doing so. For all those reasons, developing countries tend to have high rates of population growth.

 In certain countries, large areas of land can only yeild small amounts of food because....................

Choose the item among A, B, C or D that best answers the question about the passage:

"Yong Liang, two years old, is the first giant panda raised from birth in the zoo. Last month zoo keepers found the panda was suffering from serious anemia, calling for urgent blood transfusion.
 The best way, according to the zoo’s experts, to save Yong Liang from anemia would have been to transfuse blood from another panda. But it was the breeding season for giant pandas, making such a transfusion very difficult.
 But the experts found that there exists a close consanguinity, relationship by birth in the same family, between giant pandas and black bears, so they decided to try to take blood from black bears in the zoo and transfuse it to Yong Liang.
 With the help of hospitals and the Beijing Blood Donor Station, they made an experiment which proved that the red blood cells in the blood of black bears can be used.
 On the afternoon of February 15th, the first red blood cell transfusion was given to the giant panda, from 600 ml of black bear blood. Immediately the young panda started to recover."

1. Which of the following is NOT true according to the passage?

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 reason women appear to be at greater risk of developing Alzheimer’s disease than men might be due to a number of genetic, anatomical and even social influences, researchers have suggested.
      Recent figures show about 65% of those with living with dementia in the UK are women, with a similar statistic seen in the US for Alzheimer’s disease, while dementia is the leading cause of death for women in England. Alzheimer’s disease is only one of the types of dementia, but the most common form. While one explanation is that dementia risk increases with age, and women have longer life expectancies than men, new research suggests there might be more to the matter, including that protein tangles found within neurons and linked to Alzheimer’s disease might spread differently in women’s brains than men’s.
      The study, presented at the Alzheimer’s Association International Conference in Los Angeles by researchers from Vanderbilt University and which has not yet been peer-reviewed, used scans from a method called positron emission tomography. That allowed them to look at the way clumps of a protein called tau were spread in the brains of 123 men and 178 women without cognitive problems, as well as 101 men and 60 women with mild cognitive problems – although not yet diagnosed with Alzheimer’s disease. Cognitively normal older people often have small amounts of tau in certain areas of their brain.
      From the data the team could build maps showing which areas of the brain show similar signals relating to tau in the scans, suggesting they are somehow connected. “Based on that we kind of try to reconstruct the pattern of spread,” Dr Sepideh Shokouhi, who is presenting the research, told the Guardian. “It is kind of like reconstructing a crime scene.” The team says the results suggest these maps look different in women and men, suggesting tau might be able to spread more rapidly across the female brain.
     Other research presented at the conference – and also not yet peer reviewed – added weight to the idea that there might be differences between men and women that affect dementia risk. Research by scientists at the University of Miami has revealed a handful of genes and genetic variants appear to be linked to Alzheimer’s disease in just one biological sex or the other. While the actual importance of these factors has yet to be unpicked, and the study only looked at white participants, the team says it underscores that there could be a genetic reason for differences in the risk of dementia in men and women, and the way it develops.

As mentioned in paragraph 3, positron emission tomography is a method to __________.

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) ____.

(8) ____

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.
6.

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.
1.

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_____________

In the West, cartoons are used chiefly to make people laugh. The important feature of all these cartoons is the joke and the element of surprise which is contained. Even though it is very funny, a good cartoon is always based on close observation of a particular feature of life and usually has a serious purpose.

Cartoons in the West have been associated with political and social matters for many years. In wartime, for example, they proved to be an excellent way of spreading propaganda. Nowadays cartoons are often used to make short, sharp comments on politics and governments as well as on a variety of social matters. In this way, the modern cartoon has become a very powerful force in influencing people in Europe and tlie United States.

Unlike most American and European cartoons, however, many Chinese cartoon drawings in the past have also attempted to educate people, especially those who could not read and write. Such cartoons about the lives and sayings of great men in China have proved extremely useful in bringing education to illiterate and semi-literate people throughout China.

Confucius, Mencius and Laozi have all appeared in very interesting Stories presented in the form of cartoons. The cartoons themselves have thus served to illustrate the teachings of the Chinese sages in a very attractive way.

In this sense many Chinese cartoons are different from Western cartoons in so far as they do not depend chiefly on telling jokes. Often, there is nothing to laugh at when you see Chinese cartoons. This is not their primary aim. In addition to commenting on serious political and social matters, Chinese cartoons have aimed at spreading the traditional Chinese thoughts and culture as widely as possible among the people.

Today, however, Chinese cartoons have an added part to play in spreading knowledge.

They offer a very attractive and useful way of reaching people throughout the world, regardless of the particular country in which they live. Thus, through cartoons, the thoughts and teachings of the old Chinese philosophers and sages can now reach people who live in such countries as Britain, France, America, Japan, Malaysia or Australia and who are unfamiliar with the Chinese culture.

Until recently, the transfer of knowledge and culture has been overwhelmingly from the West to the East and not vice versa. By means of cartoons, however, publishing companies in Taiwan, Hong Kong and Singapore are now having success in correcting this imbalance between the East and the West.

Cartoons can overcome language barriers in all foreign countries. The vast increase in the popularity of these cartoons serves to illustrate the truth of Confucius's famous saying "One picture is worth a thousand words.”

Which of the following clearly characterizes Western cartoons?

Reading to oneself is a modern activity which was almost unknown to the scholars of the classical and medieval worlds, while during the fifteenth century the term "reading" undoubtedly meant reading aloud. Only during thenineleenthcenturydid silent reading become commonplace.
One should be wary, however, of assuming that silent reading came about simply because reading aloud was a distraction to others. Examinations of factors related to the historical development of silent reading have revealed that it became the usual mode  of reading for most adults mainly because the tasks themselves changed in character.
The last century saw a steady gradual increase in literacy and thus in the number of readers. As the number of readers increased, the number of potential listeners declined and thus there was some reduction in the need to read aloud. As reading for the benefit of listeners grew less common, so came the flourishing of reading as a private activity in such public places as libraries, railway carriages and offices, where reading aloud would cause distraction to other readers.
Towards the end of the century, there was still considerable argument over whether books should be used for information or treated respectfully and over whether the reading of  materials such as newspapers was in some way mentally weakening. Indeed, this argument remains with us still in education. However, whatever its virtues, the old shared literacy  culture had gone and was replaced by the printed mass media on the one hand and by books and periodicals for a specialised readership on the other.
By the end of the twentieth century, students were being recommended to adopt attitudes to books and to use reading skills which were inappropriate, if not impossible, for the oral reader. The social, cultural and technological changes in the century had greatly altered what the term "reading" implied.

The development of silent reading during the last century indicated..........................

 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."

4. In some cases, animals are (4)….. for their fur or for other valuable parts of their bodies.

Mark the letter A, B, C or D to indicate the underlined part that needs correction in each of the following questions.
The Principal demanded that the heaters repair immediately. Winter is coming!

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) ____

Reading to oneself is a modern activity which was almost unknown to the scholars of the classical and medieval worlds, while during the fifteenth century the term "reading" undoubtedly meant reading aloud. Only during thenineleenthcenturydid silent reading become commonplace.
One should be wary, however, of assuming that silent reading came about simply because reading aloud was a distraction to others. Examinations of factors related to the historical development of silent reading have revealed that it became the usual mode  of reading for most adults mainly because the tasks themselves changed in character.
The last century saw a steady gradual increase in literacy and thus in the number of readers. As the number of readers increased, the number of potential listeners declined and thus there was some reduction in the need to read aloud. As reading for the benefit of listeners grew less common, so came the flourishing of reading as a private activity in such public places as libraries, railway carriages and offices, where reading aloud would cause distraction to other readers.
Towards the end of the century, there was still considerable argument over whether books should be used for information or treated respectfully and over whether the reading of  materials such as newspapers was in some way mentally weakening. Indeed, this argument remains with us still in education. However, whatever its virtues, the old shared literacy  culture had gone and was replaced by the printed mass media on the one hand and by books and periodicals for a specialised readership on the other.
By the end of the twentieth century, students were being recommended to adopt attitudes to books and to use reading skills which were inappropriate, if not impossible, for the oral reader. The social, cultural and technological changes in the century had greatly altered what the term "reading" implied.

Which of the following statements is NOT TRUE according to the passage?

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.

Scionlists have observed that warmer temperatures in the spring cause flowers to..............

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

Successful students often do the following while studying. First, they have an overview before reading. Next, they look for important information and pay greater attention to it (which often needs jumping forward or backward to process information). They also relate important points to one another. Also, they activate and use their prior knowledge. When they realize that their understanding is not good, they do not wait to change strategies. Last, they can monitor understanding and take action to correct or "fix up" mistakes in comprehension.

Conversely students with low academic achievement often demonstrate ineffective study skills. They tend to assume a passive role in learning and rely on others (eg, teachers, parents) to monitor their studying, for example, low achieving students often do not monitor their understanding of content they may not be aware of the purpose of studying, and they show little evidence of looking back, or employing "fix-up strategies to fix understanding problems.

Students who struggle with learning new information seem to be unaware that they must extent effort beyond simply reading the content to understand and remember it. Children with learning disabilities do not plan and judge the quality of their studying. Their studying may be disorganized. Students with learning problems face challenges with personal organization as well. They often have difficulty keeping track of materials and assignments, following directions, and completing work on time. Unlike good studiers who employ a variety of study skills in a flexible yet purposeful manner, low-achieving students use a restricted range of study skills. They cannot explain why good study strategies are important for learning, and they tend to use the same, often ineffective study approach for all learning tasks, ignoring task content, structure or difficulty.

In compared with low-achieving students, successful students use__.

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) _____

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.

(5) ..............

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 “he” in paragraph 2 refers to _______.

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: 
We are descendents of the ice age. Periods of glaciation have spanned the whole of human existence for the past 2 million years. The rapid melting of the continental glaciers at the end of the last ice age spurred one of the most dramatic climate changes in the history of the planet. During this interglacial time, people were caught up in a cataclysm of human accomplishment, including the development of agriculture and animal husbandry. Over the past few thousand years, the Earth’s climate has been extraordinarily beneficial, and humans have prospered exceedingly well under a benign atmosphere. Ice ages have dramatically affected life on Earth almost from the very beginning. It is even possible that life itself significantly changed the climate. All living organisms pull carbon dioxide out of the atmosphere and eventually store it in sedimentary rocks within the Earth’s crust. If too much carbon dioxide is lost, too much heat escapes out into the atmosphere. This can cause the Earth to cool enough for glacial ice to spread across the land. In general the reduction of the level of carbon dioxide in the atmosphere has been equalized by the input of carbon dioxide from such events as volcanic eruptions. Man, however, is upsetting the equation by burning fossil fuels and destroying tropical rain forests, both of which release stored carbon dioxide. This energizes the greenhouse effect and causes the Earth to warm. If the warming is significant enough, the polar ice caps eventually melt. The polar ice caps drive the atmospheric and oceanic circulation systems. Should the ice caps melt, warm tropical waters could circle the globe and make this a very warm, inhospitable planet. Over the past century, the global sea level has apparently risen upwards of 6 inches, mainly because of the melting of glacial ice. If present warming trends continue, the seas could rise as much as 6 feet by the next century. This could flood coastal cities and fertile river deltas, where half the human population lives. Delicate wetlands, where many marine species breed, also would be reclaimed by the sea. In addition, more frequent and severe storms would batter coastal areas, adding to the disaster of the higher seas. The continued melting of the great ice sheets in polar regions could cause massive amounts of ice to crash into the ocean. This would further raise the sea level and release more ice, which could more than double the area of sea ice and increase correspondingly the amount of sunlight reflected back into space. The cycle would then be complete as this could cause global temperatures to drop enough to initiate another ice age.

According to the passage, what is the relationship between carbon dioxide and the Earth’s climate?