Choose the best answer:
People should eat ............... and do ............. to reduce the risk of heart disease.

 

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Love covers a range of strong and positive emotional and mental states, from the most sublime virtue or good habit, the deepest interpersonal affection to the simplest pleasure. An example of this range of (1) ____________________ is that the love of a mother differs from the love of a wife, which also differs from the love of food. Most commonly, it (2) ______________ to a feeling of strong attraction and deep emotional attachment. Love is considered to be both positive and negative; with its virtue representing human kindness, compassion, and affection, as “the unselfish loyal and benevolent concern for the good of another”; and its vice representing human moral flaw, (3) ______________ to vanity, selfishness, amour-propre, and egotism, as it potentially leads people into a type of mania, obsessiveness or codependency. It may also describe compassionate and affectionate actions (4) _____________________ other humans, one’s self or animals. In its various forms, love acts as a major facilitator of interpersonal relationships and, owing to its central psychological importance, is one of the most common themes in creative arts. Love has, supposedly, a function to keep human beings (5) ___________________ against menaces and to facilitate the continuation of the human species

Read the following passage and choose the best answer (A, B, C, D):
Set aside time each day Most of us can find 15 minutes or half an hour each day for some specific regular activity. It may be a free period or a regular wait, stay in the queue for a bus or meal - even while eating breakfast. One famous surgeon always made it a rule to spend at least 15 minutes on general reading before he went to sleep each night. Whether he went to bed at 10:00 p.m or 2:30 a.m. made no difference. Even if you cannot keep to this kind of discipline, it is a good idea to make sure you always have a general interest book in your pocket. Don’t forget it should be a book which entertains you and the English must not be too difficult for you. Checking your progress through pacing Nearly all speed reading courses have a "pacing element - some timing device which lets the student know how many words a minute he is reading. You can do this simply by looking at your watch every 5 or 10 minutes and noting down the page number you have reached. How do you know when 5 minutes have passed on your watch if you are busy reading the book? Well, this is difficult at first. A friend can help by timing you over a set period. Pace yourself every three or four days, always with the same kind of easy, general interest book. You should soon notice your habitual w. p. m rate creeping up. Check comprehension Obviously there is little point in increasing your w. p. m rate if you do not understand what you are reading. When you are consciously trying to increase your reading speed, stop after every chapter (if you are reading a novel) or every section or group of ten or twelve pages (if it is a textbook) and ask yourself a few questions about what you have been reading. If you find you have lost the thread of the story, or you cannot remember clearly the details of what was said, re-read the section or chapter. “Lightening speed” exercise Take 4 or 5 pages in the general interest book you happen to be reading at the time. Read them as fast as you possibly can. Do not bother about whether you understand or not. Now go back and read them at what you feel to be your normal w. p. m rate, the rate at which you can comfortably understand. After a “lightening speed” read through (probably around 6 w. p. m) you will usually find that your normal speed has increased -  perhaps by as much as 50 -100 w. p. m.
1. The passage recommends setting aside for reading practice ____

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As teenagers approach university level, a decision has to be made on what course to pursue. In this world of diversity, (1) ______ such a choice is not easy for both children and parents. In the old days, it was not much a problem to do the task because there were not so many diverse learning areas to choose from. Besides, there were only a few distinctive professional careers like doctor, engineer, accountant, nurse, teacher,etc.  to think about. Most higher learning usually led to a financially successful life. (2) ______, the cost of education was not so high. Today’s world is entirely different from the things (3) ______ have just been described.  The job market is constantly changing due to innovative technology and new (4) ______. Meanwhile, most teenagers have difficulty in identifying their own interests. There are a variety of well- organized career talks and student counseling workshop to guide and help teenagers (5) ______ what course to take. Furthermore, psychological tests are also used.  Certain instruments such as surveys, interviews and computer software can help to find out preferences, interests, or learning styles of the students.

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Continuing education is required for workers to stay current with the latest developments, skills, and new technologies required for their fields. Certain professions also require continuing education to comply with laws, remain licensed or certified, or maintain membership in an association or licensing body. Many careers require continuing education. For example, teachers, real estate agents, and engineers are required to have a base of education and then receive updated education as they continue to work in their fields. Nursing, pharmacy, accounting, and criminal justice are additional fields in which professionals must continue to develop the skills necessary for ever-changing environments. For nurses, there are typically two types of continuing education. The first is required for them to remain licensed in their states. The second type of continuing education allows them to get more advanced degrees and qualify for higher-level nursing positions. In the fastpaced pharmacy field, continuing education is important for career growth and licensure. Pharmacists need continuing education to renew their state licenses. Continuing education focuses on subject areas in health care, including pharmacology, patient counseling, regulatory issues, and other topics that contribute to professional pharmacy practice.  Certified public accountants (CPAs) must meet continuing education requirements established by the State Board of Accountancy of the states where their CPA licenses are held. The requirements vary from state to state. The American Institute of CPAs (AICPA) also requires certain continuing education for CPAs to maintain membership. Meanwhile, criminal justice professionals need to stay up-to-date on the new laws, procedures, and technologies to reinforce the knowledge they have already gained. Criminal justice and legal fields include a variety of jobs, such as probation and parole officers, summary court officials, emergency management personnel, and crime scene technicians. Many of these careers require an undergraduate degree for entry, and then professionals must complete continuing education courses as they progress in their careers. Crime scene investigators and evidence technicians must maintain certifications specific to the collection, processing, and maintenance of evidence. Traffic crash reconstructionists must maintain accredited certifications. Emergency management professionals must complete and maintain certifications for their respective states and the Federal Emergency Management Agency (FEMA). Howard concluded “Today’s professionals must, therefore, commit to a ‘life-long learning’ philosophy that enhances effectiveness, diagnose and more quickly solves problems, while moving away from the traditional autocratic management styles.” Whether it is required or not, continuing education can be important for career satisfaction.  
6. Which of the following statements is TRUE, according to the passage?

Choose the best answer:
We ____ our classroom for the upcoming Teachers' Day, but there's still a lot to do.

Rewrite the sentence:
We couldn’t reach the house because the road was flooded.

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Globalization can be seen as increased economic, cultural and technological exchange between countries. Examples might be McDonald's in Calcutta and Japanese motor technology in Britain. Many international organizations are pro-globalization, while many others are anti- ones. The main organizations against globalization are the environmental organizations, such as Friends of the Earth and reenpeace, who put forward the belief that globalization harms the environment. In general, these organizations blame global corporations for global warning and the depletion of natural resources. The most obvious is oil and gas, but there are others such as tropical rainforests, which are cut down for timber, and the resources of the sea, which may be affected by pollution. Organizations which represent developing countries, including international aid agencies such as Oxfam, are also against globalization. They are concerned that the global organizations, such as the International Monetary Fund (IMF) and the World Bank, are not doing enough to help the poor and indeed, may be adding to their problems. Some are critical of the World Trade Organization (WTO). They argue that the WTO is making difficult for poor countries to protect and build their own industries. On the contrary, many organizations are in favor of globalization. Perhaps the most important one is the WTO. This organization was set up in 1995 and has 123 member countries. It administers the rules of international trade agreed by its member countries. The WTO's rules make it difficult for a country to favor their own industry over imports from other countries. The WTO argues that the growth of trade between countries increases the wealth of everyone. Trade allows those who can produce goods most cheaply to do so, thus giving everyone the best possible price. Another pro-globalization organization is IMF. This was established after World War II in 1946. It aims to promote international cooperation on finance and provide temporary help for countries suffering financial problems. The IMF has 182 member countries. Finally, the United Nations, which was established after the Second World War, has become a promoter of globalization. It aims to  promote a shared set of values in the areas of labour standards, human rights and environmental practices between the UN and the business community.
5. According to the passage, which of the following is NOT true?

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

Nowadays, industry  turns out more products at greater speed and with least labor to meet the demands of the rapidly increasing population

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Sociologists have been carrying out research into the social pressures of being a teenager. Many adolescents are unhappy at school because they find it difficult to (1) ______ friends. This stress can bring on illness or result in poor grades. They may also worry about their appearance and often feel (2) ______ enormous pressure to dress, talk and behave the same as (3) ______. This phenomenon is called peer pressure, and it is very common in today’s society. Advertising contributes a lot to the social pressures teenagers feel. Advertisers know how important it is to feel that you belong to a group when you are in your teens, so they try to persuade teenagers that certain products will make them (4) ______ with their classmates. Sadly, many teenagers act irresponsibly and even do dangerous things just to make others accept them. Peer pressure is often the reason for teenage smoking, drug (5) ______ or dangerous driving. Teenagers need to learn to say no to social pressure and to find friends who they can talk things over with when they have a problem

Read the following passage and choose the best answer (A, B, C, D):
Sociologists have been carrying out research into the social pressures of being a teenager. Many adolescents are unhappy at school because they find it difficult to (1) ______ friends. This stress can bring on illness or result in poor grades. They may also worry about their appearance and often feel (2) ______ enormous pressure to dress, talk and behave the same as (3) ______. This phenomenon is called peer pressure, and it is very common in today’s society. Advertising contributes a lot to the social pressures teenagers feel. Advertisers know how important it is to feel that you belong to a group when you are in your teens, so they try to persuade teenagers that certain products will make them (4) ______ with their classmates. Sadly, many teenagers act irresponsibly and even do dangerous things just to make others accept them. Peer pressure is often the reason for teenage smoking, drug (5) ______ or dangerous driving. Teenagers need to learn to say no to social pressure and to find friends who they can talk things over with when they have a problem

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Certainly no creature in the sea is odder than the common sea cucumber. All living creature, especially human beings, have their peculiarities, but everything about the little sea cucumber seems unusual. What else can be said about a bizarre animal that, among other eccentricities, eats mud, feeds almost continuously day and night but can live without eating for long periods, and can be poisonous but is considered supremely edible by gourmets? For some fifty million years, despite all its eccentricities, the sea cucumber has subsisted on its diet of mud. It is adaptable enough to live attached to rocks by its tube feet, under rocks in shallow water, or on the surface of mud flats. Common in cool water on both Atlantic and Pacific shores, it has the ability to such up mud or sand and digest whatever nutrients are present. Sea cucumbers come in a variety of colors, ranging from black to reddish-brown to sand-color and nearly white. One form even has vivid purple tentacle. Usually the creatures are cucumber-shaped-hence their name-and because they are typically rock inhabitants, this shape, combine with flexibility, enables them to squeeze into crevices where they are safe from predators and ocean currents. Although they have voracious appetites, eating day and night, sea cucumbers have the capacity to become quiescent and live at a low metabolic rate-feeding sparingly or not at all for long periods, so that the marine organisms that provide their food have a chance to multiply. If it were not for this faculty, they would devour all the food available in a short time and would probably starve themselves out of existence. But the most spectacular thing about the sea cucumber is the way it defends itself. Its major enemies are fish and crabs, when attacked, it squirts all its internal organs into the water. It also casts off attached structures such as tentacles. The sea cucumber will eviscerate and regenerate itself if it is attached or even touched; it will do the same if the surrounding water temperature is too high or if the water becomes too polluted.
4. According to the passage, why is the shape of sea cucumbers important?

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Modern society has given significant attention to the promises of the digital economy over the past decade. But it has given little attention to its negative environmental footprint. Our smartphones rely on rare earth metals, and cloud computing, data centers, artificial intelligence and cryptocurrencies consume large amounts of electricity, often sourced from coal-fired power plants. These are crucial blind spots we must address if we hope to capture the full potential of the digital economy. Without urgent system-wide actions, the digital economy and green economy will be incompatible with each other and could lead to more greenhouse gas emissions, accelerate climate change and pose great threats to humanity. The world’s data centers-the storehouses for enormous quantities of information - consume about three percent of the global electricity supply (more than the entire United Kingdom), and produce two percent of global greenhouse gas emissions-roughly the same as global air travel. A report by Greenpeace East Asia and the North China Electric Power University found that China’s data centers produced 99 million tonnes of carbon dioxide in 2018, the equivalent of about 21 million cars driven for one year. Greenhouse gases aren’t the only type of pollution to be concerned about.Electronic waste (e-waste), which is a byproduct of data center activities, accounts for two percent of solid waste and 70 percent of toxic waste in the United States. Globally, the world produces as much as 50 million tonnes of electronic e-waste a year, worth over US$62.5 billion and more than the GDP of most countries. Only 20 percent of this e-waste is recycled. The world and its intractable challenges are not linear-everything connects to everything else. We must raise awareness about these major blind spots, embrace systems leadership (leading across boundaries), boost circular economy ideas (decoupling economic activity from the consumption of finite resources), leverage an eco-economics approach (an environmentally sustainable economy) and encourage policy-makers to explore the interrelationships between government-wide, system-wide and societal results. We must also consider collective problem-solving by bringing together diverse perspectives from both the Global North and the Global South. We should take an inventory of the global and local damages caused by electronic devices, platforms and data systems, and frame issues about the digital economy and its environmental impact in broad societal terms.
5. The word “linear” in paragraph 4 is closest in meaning to _______

In the mid - nineteenth century, the United States had tremendous natural resources that could be exploited in order to develop heavy industry. Most of the raw materials that are valuable in the manufacture of machinery, transportation facilities, and consumer goods lay ready to be worked into wealth. Iron, coal, and oil - the basic ingredients of industrial growth - were plentiful and needed only the application of technical expertise, organizational skill, and labor.

One crucial development in this movement toward industrialization was the growth of the railroads. The railway network expanded rapidly until the railroad map of the United States looked like a spider's web, with the steel filaments connecting all important sources of raw materials, their places of manufacture, and their centers of distribution. The railroads contributed to the industrial growth not only by connecting these major centers, but also by themselves consuming enormous amounts of fuel, iron, and coal.

Many factors influenced emerging modes of production. For example, machine tools, the tools used to make goods, were steadily improved in the latter part of the nineteenth century - always with an eye to speedier production and lower unit costs. The products of the factories were rapidly absorbed by the growing cities that sheltered the workers and the distributors. The increased urban population was nourished by the increased farm production that, in turn, was made more productive by the use of the new farm machinery. American agricultural production kept up with the urban demand and still had surpluses for sale to the industrial centers of Europe.

The labor that ran the factories and built the railways was recruited in part from American farm areas where people were being displaced by farm machinery, in part from Asia, and in part from Europe. Europe now began to send tides of immigrants from eastern and southern Europe - most of whom were originally poor farmers but who settled in American industrial cities. The money to finance this tremendous expansion of the American economy still came from European financiers for the most part, but the American were approaching the day when their expansion could be financed in their own " money market".

Which of the following in NOT true of United States farmers in the nineteenth century?

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Previously, people often only considered second-hand smoke as a welfare issue, focusing on the smell and the irritation that tobacco smoke causes to eyes, nose and throat. But now the weight of evidence for much more serious risks to health from second-hand smoke has grown too great to ignore. Tobacco smoke contains around 4,000 chemicals, including arsenic, benzene, formaldehyde and ammonia. Around 60 of these chemicals are known or suspected to cause cancer. Many of the toxic chemicals are actually more concentrated in the smoke that’s given off by the burning tip of a cigarette (sidestream smoke). Around 85 per cent of the smoke in a room where people are smoking is the more toxic sidestream smoke. By breathing in it in the atmosphere, the non-smoker is exposed to many of the same health risks as the smoker. The best known risk to smokers, lung cancer, is also more common in people regularly exposed to second-hand smoke. The Government’s Scientific Committee on Tobacco and Health (SCOTH) reported in 1998 that exposure to second-hand smoke increases the risk of lung cancer in non-smokers by 20-30 per cent. Even though they inhale only 1% of the smoke, non-smokers exposed to second-hand smoke may suffer 25 per cent of the increased risk of heart disease associated with active smoking (one recent study suggests it might be as much as 50 per cent). Just 30 minutes of breathing second-hand smoke can reduce the coronary blood supply of a non-smoker to the same level as that of a smoker. A study in New Zealand found that exposure to second-hand smoke increases the risk of stroke by 82 per cent in non-smokers. This is a serious concern, as stroke is such a common condition. Moreover, around 3.4 million people in the UK have asthma and for most of these, tobacco smoke is a trigger for an asthma attack. For someone with asthma, just one hour of exposure to second-hand smoke can cause a 20 per cent deterioration in lung function. During pregnancy, breathing in second-hand smoke increases the risk of having a baby with a low birth weight. Small babies are at much greater risk of infections and other health problems. A recent review of international research on the immediate health impact of smokefree workplace legislation found rapid and dramatic improvements. Air quality, respiratory health and levels of heart attacks and heart disease all improved substantially within months of the legislation being introduced.
7. The article states 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.

   Family life in the United States is changing. Thirty or forty years ago, the wife was called a "housewife". She cleaned, cooked, and cared for the children. The husband earned the money for the family. He was usually out working all day. He came home tired in the evening, so he did not do much housework. And he did not see the children very much, except on weekends.

   These days, however, more and more women work outside the home. They cannot stay with the children all day. They, too, come home tired in the evening. They do not want to spend the evening cooking dinner and cleaning up. They do not have time to clean the house and do the laundry. So who is going to do the housework now? Who is going to take care of the children?

   Many families solve the problem of housework by sharing it. In these families, the husband and wife agree to do different jobs around the house, or they take turns doing each job. For example, the husband always cooks dinner and the wife always does the laundry. Or the wife cooks dinner on some nights and the husband cooks dinner on other nights.

   Then there is a question of the children. In the past, many families got help with child care from grandparents. Now families usually do not live near their relatives. The grandparents often are too far away to help in a regular way. More often, parents have to pay for child care help. The help may be a babysister or a day-care center. The problem with this kind of help is the high cost. It is possible only for couples with jobs that pay well.

   Parents may get another kind of help from the companies they work for. Many companies now let people with children work part-time. That way, parents can spend more time with their children. Some husbands may even stop working for a while to stay with the children. For these men there is a new word: They are called "househusband". In the United States more ans more men are becoming househusband every year.

   These changes in the home mean changes in the family. Fathers can learn to understand their children better, and the children can get to know their fathers better. Husbands and wives may also find changes in their marriage. They, too, may have a better understanding of each other.

It can be inferred from paragraph 4 that__________.

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Bagpipe music played, wreaths were sent and Amazing Grace was sung. A  black shroud was laid upon a makeshift urn. It was a funeral, of course, for which such displays of respect are common. But in this case, the people living in a small Nova Scotia community had gathered to pay their respects not to a person who had died, but to a post office.  The grief might have been hard for outsiders to understand, but not for those living in Head of St. Margaret’s Bay, N.S., where the post office run by Verna Dunlop was a big part of their small, tight-knit community. The post office, which had been located in the back of Dunlop’s home, was not just a utilitarian service kiosk where residents had to go to pick up their mail. According to locals, it was also a community hub where people gathered to catch up on the town gossip, or to enjoy a cup of the coffee the postmaster had been brewing for them. “It’s really the centre of the village,” said one woman, explaining what the post office meant to the people living there.  There had been a post office located in Head of St. Margaret’s Bay since before Confederation. And local residents spent months fighting to keep the one they had. But Canada Post made the decision to close it, as it was losing money. It was replacing the post office with sets of newly installed super mailboxes.  Many people in town weren’t convinced the coming changes were for the better. “We do not want those super mailboxes. We want to have a community life,” he said. At the mock funeral, Dunlop choked up as she said she hoped “this is going to stop,” alluding to the fact that it wasn’t just Head of St. Margaret’s Bay that was losing its post office. “We hope that the way of life that we’re used to we can keep,” she added. Canada Post had closed 40 such rural post offices that year and had long-term plans to close more than 5,000 of them across the country. “Just as Verna Dunlop’s post office came to symbolize for these people the best qualities of rural life, so does its passing remind them of the steady erosion of that way of life,” said Evans.
7. Which of the following statements is TRUE, according to the passage?

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There have never been so many people living in cities in quake zones because the worse the damage can be from a big quake, bringing fires, tsunamis, and the loss of life, property, and maybe an entire city. We understand how earthquakes happen but not exactly where or when they will occur. Until recently, quakes seemed to occur at random. In Japan, government research is now showing that quakes can be predicted. At the Earthquake Research Institute, University of Tokyo, Koshun Yamaoka says earthquakes do follow a pattern—pressure builds in a zone and must be released. But a colleague, Naoyuki Kato, adds that laboratory experiments indicate that a fault slips a little before it breaks. If this is true, predictions can be made based on the detection of slips. Research in the U.S. may support Kato’s theory. In Parkfield, California earthquakes occur about every 22 years on the San Andreas fault. In the 1980s, scientists drilled into the fault and set up equipment to record activity to look for warning signs. When an earthquake hit again, it was years off schedule. At first the event seemed random but scientists drilled deeper. By 2005 they reached the bottom of the fault, two miles down, and found something. Data from two quakes reported in 2008 show there were two “slips’—places where the plates widened—before the fault line broke and the quakes occurred. We are learning more about these destructive events every day. In the future we may be able to track earthquakes and design an early-warning system. So if the next great earthquake does happen in Tokai, about 100 miles southwest of Tokyo, as some scientists think, the citizens of Tokai may have advance warning
1. What is the main idea of the passage?

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In the last five decades or so, the media and its influence on the societies, has grown (1)_______ with the advance of technology. First there was the telegraph and the post offices, then the radio, the newspaper, magazines, television and now the internet and the new media including palmtops, cell phones etc. There are positive and negative influences of mass media, which we must understand as a responsible person of a society. Before (2)___________ the influence of mass media on society it is imperative to explain the three basic functions of mass media; they are providing news/information, entertainment and education. The first and foremost function of the media in a society is to provide news and information to the masses, that is why the present era is some time termed as the information age (3)__________. People need news/information for various reasons, on one hand it can be used to socialize and on the other to make decisions and formulate opinions. Entertainment would be the other function of the mass media (4)______ it is mostly used by the masses to amuse them in present day hectic environment. Educating the masses about their rights, moral, social and religious obligations is another important function of mass media, which needs no emphasis. In present era of (5)__________ , majority of people in the society depends on information and communication to remain connected with the world and do our daily activities like work, entertainment, health care, education, socialization, travelling and anything else that we have to do

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For 150 years scientists have tried to determine the solar constant, the amount of solar energy that reaches the Earth. Yet, even in the most cloud-free regions of the planet, the solar constant cannot be measured precisely. Gas molecules and dust particles in the atmosphere absorb and scatter sunlight and prevent some wavelengths of the light from ever reaching the ground. With the advent of satellites, however, scientists have finally been able to measure the Sun's output without being impeded by the Earth's atmosphere. Solar Max, a satellite from the National Aeronautics and Space Administration (NASA), has been measuring the Sun's output since February 1980. Although a malfunction in the satellite's control system limited its observation for a few years, the satellite was repaired in orbit by astronauts from the space shuttle in 1984. Max's observations indicate that the solar constant is not really constant after all. The satellite's instruments have detected frequent, small variations in the Sun's energy output, generally amounting to no more than 0.05 percent of the Sun's mean energy output and lasting from a few weeks. Scientists believe these fluctuations coincide with the appearance and disappearance of large groups of sunspots on the Sun's disk. Sunspots are relatively dark regions on the Sun's surface that have strong magnetic fields and a temperature about 2,000 degrees Fahrenheit cooler than the rest of the Sun's surface. Particularly large fluctuations in the solar constant have coincided with sightings of large sunspot group. In 1980, for example, Solar Max's instrument, registered a 0.3percent drop in the solar energy reaching the Earth. At that time a sunspot group covered about 0.6 percent of the solar disk, an area 20 times larger than the Earth's surface. Long-term variations in the solar constant are more difficult to determine. Although Solar Max's data have indicated a slow and steady decline in the Sun's output, some scientists have thought that the satellite's aging detectors might have become less sensitive over the years, thus falsely indicating a drop in the solar constant. This possibility was dismissed, however, by comparing Solar Max's observations with data from a similar instrument operating on NASA's Nimbus 7 weather satellite since 1978.
8. Why did scientists think that Solar Max might be giving unreliable information?

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Pollutants in the air aren’t always visible and come from many different sources. Smog hanging over cities is the most familiar and obvious form of air pollution. But there are different kinds of pollution - some visible, some invisible - that contribute to global warming. Generally any substance that people introduce into the atmosphere that has damaging effects on living things and the environment is considered air pollution. Carbon dioxide, a greenhouse gas, is the main pollutant that is warming Earth. Though living things emit carbon dioxide when they breathe, carbon dioxide is widely considered to be a pollutant when associated with cars, planes, power plants, and other human activities that involve the burning of fossil fuels such as gasoline and natural gas. In the past 150 years, such activities have pumped enough carbon dioxide into the atmosphere to raise its levels higher than they have been for hundreds of thousands of years. Other greenhouse gases include methane - which comes from such sources as swamps and gas emitted by livestock - and chlorofluorocarbons (CFCs), which were used in refrigerants and aerosol propellants until they were banned because of their deteriorating effect on Earth’s ozone layer. Another pollutant associated with climate change is sulfur dioxide, a component of smog. Sulfur dioxide and closely related chemicals are known primarily as a cause of acid rain. But they also reflect light when released in the atmosphere, which keeps sunlight out and causes Earth to cool. Volcanic eruptions can spew massive amounts of sulfur dioxide into the atmosphere, sometimes causing cooling that lasts for years. In fact, volcanoes used to be the main source of atmospheric sulfur dioxide; today people are. Industrialized countries have worked to reduce levels of sulfur dioxide, smog, and smoke in order to improve people’s health. But a result, not predicted until recently, is that the lower sulfur dioxide levels may actually make global warming worse. Just as sulfur dioxide from volcanoes can cool the planet by blocking sunlight, cutting the amount of the compound in the atmosphere lets more sunlight through, warming the Earth. This effect is exaggerated when elevated levels of other greenhouse gases in the atmosphere trap the additional heat.
5. What has been the main source of atmospheric sulfur dioxide recently?