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Whether a species is endangered—meaning at risk of extinction—depends on which definition you use. The International Union for Conservation of Nature’s Red List of Threatened Species classifies an animal as endangered when its numbers in the wild have dropped so low that it’s at “extremely high risk” of extinction. Meanwhile, the United States’ Endangered Species Act of 1973 takes into consideration any destruction to a species’ habitat, whether it has been over-consumed, any disease or predation that threaten it, whether any other man-made factors put it in danger, and what policies currently exist to protect it. When members of the public or a state agency propose to the U.S. Fish & Wildlife Service or the National Marine Fisheries Service that a species be listed as endangered under the law, research and management plans are formed to help those species survive. It is illegal under the Endangered Species Act to capture, hunt, shoot, or otherwise harm an animal that’s listed as endangered. Sometimes, federal agencies decide that although a species could be considered endangered, other species are higher priorities. In those cases, the animal or plant gets limited protections. One animal whose numbers have increased through conservation is the bald eagle. There were only about 500 bald eagles in the continental United States in the 1960s because of pesticides that damaged the shells of their eggs. Conservation efforts including captive breeding programs, habitat protection, and a ban on the insecticide DDT helped the bald eagle’s numbers soar back into the thousands. Another is the giant panda, which was declared no longer endangered in 2016 thanks to 50 years of efforts to save it. U.S. Rep. John Dingell, who wrote the Endangered Species Act, argued that “only natural extinction is part of natural order.” Scientists believe that 227 species - including the grizzly bear, the peregrine falcon and the gray wolf - were saved from extinction in the first 33 years of the law’s existence. Still, critics argue that the act is expensive and ineffective because it protects so many species. Several federal courts have heard and rejected arguments that the Endangered Species Act is unconstitutional, and members of Congress have tried to weaken the law in small ways.
8. Which of the following can be inferred from the passage?

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Advances in mobile technology and social networking websites mean we spend more time online than ever before. If Facebook were a country, it would be the third largest in the world by population (The Economist, 2010). It is (1) ______ not surprising that so many psychologists, sociologists, and others are eager to give their thoughts on how this is impacting negatively on our society. The biggest criticism levelled at social networking is that young people are losing their offline friends to online friends (2) ______ are unable to provide the same deep connection and emotional support. However, a lot of research shows these criticisms are generally (3) ______. Allen et al. (2010) discovered that it is socially adjusted adolescents who are more likely to have a networking profile than those who are not. One study by the Pew Internet and American Life Project (2009) found that people are not (4) ______ offline friends with online companions but are using them to support their offline relationships. The study also found that social networks allow us to have discussions with a much more diverse set of people than in the real world, so we share knowledge with people from a wide (4) ______ of backgrounds.

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According to the American Red Cross, there’s a 97% chance that someone you know will need a blood transfusion. Blood donors — especially donors with certain blood types — are always in demand. To donate blood, the American Red Cross requires that people be at least 17 years old and weigh more than 110 pounds. (In some states, the age is 16 with a parent’s permission.) Donors must be in good health and will be screened for certain medical conditions, such as anemia. Donors who meet these requirements can give blood every 56 days. Blood donation starts before you walk in the door of the blood bank. Eat a normal breakfast or lunch — this is not a good time to skip meals — but stay away from fatty foods like burgers or fries. And be sure to drink plenty of water, milk, or other liquids. Before donating, you’ll need to answer some questions about your medical history, and have your temperature, pulse, blood pressure, and blood count checked. The medical history includes questions that help blood bank staff decide if a person is healthy enough to donate blood. They’ll probably ask about any recent travel, infections, medicines, and health problems. Donated blood gets tested for viruses, including HIV (the virus that causes AIDS), hepatitis B, hepatitis C, syphilis, and West Nile virus. If any of these things are found, the blood is destroyed. Because blood can be infected with bacteria as well as viruses, certain blood components are tested for contamination with bacteria as well.  Are there any risks? A person can’t get an infection or disease from giving blood. The needles and other equipment used are sterile and they’re used only on one person and then thrown away. The U.S. Food and Drug Administration (FDA) regulates U.S. blood banks. All blood centers must pass regular inspections in order to keep operating. Sometimes people who donate blood notice a few minor side effects like nausea, lightheadedness, dizziness, or fainting, but these symptoms usually go away quickly. The donor’s body usually replaces the liquid part of blood (plasma) within 72 hours after giving blood. It generally takes about 4–8 weeks to regenerate the red blood cells lost during a blood donation. An iron-fortified diet plus daily iron tablets can help rebuild a donor’s red blood supply. The Red Cross estimates that 15% of all blood donors in the United States are high school or college students — an impressive number when you consider you have to be 16 or 17 to donate blood. If you are eligible and want to donate blood, contact your local blood bank or the American Red Cross for more information on what’s involved. You could save someone’s life.  
1. What is the purpose of the writer in the passage?

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Interacting with friends through the internet is fun.

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There are a number of initiatives, some already introduced and some in the pipeline,  that are specifically designed to ensure that the economic value of nature is recognised. One example is reduced emissions from deforestation and forest degradation, under  which forest owners are paid not to cut down trees. A number of governments across the world have committed hundreds of millions of dollars to these projects. Another is habitat banking, the market for which currently stands at around $3bn in the US, where companies that degrade natural areas are forced to restore nature elsewhere. Trade in forest conservation obligations in Brazil and ground-water salinity credits in Australia have also proved successful. Alongside these schemes and those like them, there are various compensation arrangements that make those causing environmental damage pay for it, just like carbon credits that currently exist. Exemptions from these various taxes, charges and fees, as well as subsidies, are also used to encourage environmentally responsible behaviour.  There is also growing pressure for companies to begin incorporating the costs of the damage that they do to the Earth’s natural resources into their profit and loss accounts. Only by incorporating these costs into their accounts, many argue, will companies be forced to reduce their impact on the natural world. "Directors’ bonuses don’t have to be included in company accounts from a pure profit and loss point of view, but they are. Environmental externalities should be the same," says Pavan Sukhdev, a career banker and team leader of the United Nations’ The Economics of Ecosystems and Biodiversity study.  “This is not a straightforward process and needs standard methodologies accepted by everyone, but it could be achieved within 10 years.” The next step would be to incorporate environmental assets into national accounts. 
5. According to paragraph 3, why do companies have to include green fee in their financial records?

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Some cities are located by chance. A wagon breaks down, the driver spends some  time in repairs, finds that he is in a congenial spot, and settles down. Later another person builds a house near his, and later someone adds an inn. Someone else starts selling farm produce there. Soon there is a little market, which grows to a town, and later to a city.  Other places were destined by nature to become cities. London, for example, is on what is called the head of navigation - the point where it becomes too difficult for oceangoing ships to continue upriver, and must transfer their cargoes. As with London, the head of navigation is also the point where the river can be conveniently bridged. In fact, the location of a bridge is often the reason for the birth of a town - as Cambridge or Weybridge in England show. Again, a good harbour will generally lead to a city growing up about it. New York and San Francisco began life as ports, as did Cape Town in South Africa. Some places were created mainly for military purposes, such as Milan, and the host of English cities finishing with - cester, which is derived from castra which means camp in Latin. Chester itself, created to guard the Welsh border, is a very good example. Other such military bases are Manchester, Doncaster, and of course, Newcastle.  A few cites are not created by accident, but by intention. This was the case with Milton Keynes in England, but the most famous examples of such cities are capitals. Brasilia, Canberra and Washington are capitals created in modern times, but even their greatest admirers will admit that they lack a certain character. It is no co-incidence that there are famous pop songs about New York, (“New York, New York”) Chicago (“My kind of Town”) San Francisco (“Going to San Francisco”) and many other US cities, but none about the nation’s capital. On the other hand any Londoner can give you at least three songs about the place.
1. This reading passage is mainly about ____

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He invited me to join his trip , but I ______ down his invitation.

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Taking piano lessons and solving math puzzles on a computer significantly improve specific math skills of elementary schoolchildren, according to a new study. The results, (1)______ were published in the journal Neurological Research, are the latest in a series that links musical training to the development of higher brain functions. Researchers worked with 135 second-grade students at a school in Los Angeles after (2)______ a pilot study with 102 students. Children that were given four months of piano training as well as time playing (3)______ newly designed computer software scored 27 percent higher on math and fraction tests than other children. Piano instruction is thought to enhance the brain's "hard wiring" for spatial-temporal reasoning, or the ability to visualise and transform objects in space and time, says Professor Gordon Shaw, who led the study. At the same time, the computer game allows children to solve geometric and math puzzles that boost their ability to (4)______ shapes in their mind. The findings are significant (5)______ a grasp of proportional math and fractions is a prerequisite to math at higher levels, and children who do not master these areas of math cannot understand more advanced math that is critical to high-tech fields.

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Zoos used to be primarily a place for people to see wild animals they had never seen.  Now, however, zoos serve a new purpose – to be captive-breeding programs for endangered animals. There are less than a hundred Sumatran rhinos worldwide, and three were born in Cincinnati Zoo. When old enough, one of the males was sent to Way Kamabas National Park in Sumatra and this helped to start the process of re-populating his species in the wild and saving it from the extinction.  Other zoos have started captive-breeding programs as well. Zoos have saved the Arabian onyx, the black-footed ferret, the red wolf, the Guam rail, and the California condor. But the cost of the programs for saving the threatened animals is not cheap. The condor program alone costs up to $2 million a year. While it is mostly large-city zoos involved in captive breeding, smaller zoos do their part. The Miller Park Zoo in Bloomington, Illinois, is working on breeding the endangered, and small. Mount Graham red squirrel.  Zoos have always been involved in animal conservation to some degree, but the question of which animals to save is a big one. Endangered animals may not be the most exciting to see in a zoo, and to di conservation work the zoos must survive financially. Space is a problem as well. A zoo might be able to save a small number of large animals or a large number of small ones. Currently, the most threatened group of animals is amphibians. Zoos realize that visitors may not want to see frogs, salamanders, or other small animals and may only pay to see rhinos, lions, and tigers. Some scientists believe zoos should be less tourist attractions and more conservation sanctuaries. Thus, although zoos continue to do good work, they still confront tricky questions. There are a limited number of animals that can be cared for in zoos, and that means many species on the edge of extinction may not survive. The Sumatran orangutan and a thousand other threatened species have not made it into a captive-breeding program, but the species will continue to exist. How? In the Frozen Zoo. Cells from these animals are stored in the San Diego Zoo Institute for Conservation Research in liquid nitrogen. Only one animal in the Frozen Zoo is presently extinct, but many others are at dire risk. In the Frozen Zoo, however, the cells of animals will be preserved for study through their genetic material.
7. The underlined word “confront” in the passage is closet in meaning to __________

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The issue of equality for women in British society first attracted national attention in the early 20th century, when the suffragettes won for women the right to vote. In the 1960s feminism became the subject of intense debate when the women's liberation movement encouraged women to reject their traditional supporting role and to demand the equal right with men in areas such as employment and play. Since then, the gender gap between the sexes has been reduced. The Equal Pay Act of 1970, for instance, made it illegal for woman to be paid less than men for doing the same work, and in 1975 the Sex Discrimination Act aimed to prevent either sex having an unfair advantage when applying forjobs. In the same year the Equal Opportunities Commission was set up to help people claim their rights to equal treatment and to publish research and statistics to show where improvements in opportunities for women need to be made. Women now have much better employment opportunities, though they still tend to get less well-paid jobs than men, and very few are appointed to top jobs in industry. In the US the movement that is often called the"first wave of feminism"began in the 1800s. Susan B. Anthony worked for the right to vote, Margaret Sanger wanted to provide women with the means of contraception so that they could decide whether or not to have children, and Elizabeth Blackwell, who had to fight for the chance to become a doctor, wanted to have greater opportunities to study. Many feminists were interested in other social issues. The second wave of feminism began in 1960s. Women like Betty Friedan and Gloria Steinem became associated with the fight to get equal rights and opportunities for women under law. An important issue was the Equal Rights Amendment (ERA), which was intended to change the Constitution. Although the ERA was not passed, there was progress in other areas. It became illegal for employers, schools, clubs, etc... to discriminate against women. But women still find it hard to advance beyond a certain point in their career, the so-called glass ceiling that prevents them from having high level jobs. Many women also face the problem of the second shift, i.e. the household chores. In the 1980s, feminism became less popular in the US and there was less interest in solving the remaining problems, such as the fact that most women still earn much less than men. Although there is still discrimination, the principle that it should not exist is widely accepted.
3. Susan B. Anthony, Margaret Sanger, and Elizabeth Blackwell are mentioned as .......

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Adharanand Finn is a British journalist and a keen runner. Recently, he did the Fluorspar run in Kenya with a group of top Kenyan athletes. Here is the story he told the press after the event. The route of the Fluorspar run is exactly 21 km long and is uphill from start to finish. When I arrived at the start of the run at the bottom of the hill, the morning sun was up, and it was already hot. The ten athletes and I stood together for a group photograph and then immediately started our run up to the top. Most of the athletes who live in this part of Kenya have done it at least once. After about five minutes, I was already starting to fall behind other runners. I’ve never been that good at hill climbing, so I always knew I’d find it thorny. ‘Sure and steady,’ I told myself as I ran along, avoiding the biggest stones and trying to take the shortest line up the hill. But whenever I looked up, the others were further ahead, until soon they disappeared completely. At first I felt fine, but towards the end I began to feel a bit weak and strange. I don’t know now if I was imagining things but the people I passed, who were travelling down the road, seemed to be laughing at me. Finally, I reached the top. The rest of the runners were sitting on the grass, drinking lemonade and eating peanuts and boiled eggs. It took me one hour and fifty eight minutes, which is not bad at all. The others told me kindly that anyone who can run it in under two hours is very strong. They completed it much faster, in around one hour 30 minutes. I honestly have no idea how they do it.  
5. What is the writer doing in this text?

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.

   As viewed from space, Earth’s distinguishing characteristics are its blue waters and white clouds. Enveloped by an ocean of air consisting of 78% nitrogen and 21% oxygen, the planet is the only one in our solar system known to harbor life. Circling the Sun at an average distance of 149 million kilometers (93 million miles), Earth is the third planet from the Sun and the fifth largest planet in the solar system.

   Our planet’s rapid spin and molten nickel-iron core give rise to an extensive magnetic field which, coupled the atmosphere, shields us from nearly all of the harmful radiation coming from the Sun and other stars. Earth’s atmosphere protects us from meteors as well, most of which burn up in the Earth’s atmosphere before they can strike the surface. The planet active geological processes have left no evidence of the ancient pelting it almost certainly received soon after it formed about 4.6 billion years ago. The Earth has a single natural satellite – the moon.

Which of the following helps to create the Earth’s magnetic fields?

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Diseases are a natural part of life on earth. If there were no diseases, the population would grow too quickly, and there would not be enough food or other resources, so in a way, diseases are natural ways of keeping the Earth in balance. But sometimes they spread very quickly and kill large numbers of people. For example, in 1918, an outbreak of the flu across the world, killing over 25 million people only in six months. Such terrible outbreaks of a diseases are called pandemics. Pandemics happen when a disease changes in a way that our bodies are not prepared to fiht. In 1918, a new type of fl virus appeared. Our bodies had no way to fiht this new flu virus, and so it spread very quickly and killed large numbers of people. While there have been many different pandemic diseases throughout history, all of them have a new thing in common. First, all pandemic diseases spread from one person to another very easily. Second, while they may kill many people, they generally do not kill people very quickly. A good example of this would be the Marburg virus. The Marburg virus is an extremely infectious disease. In addition, it is deadly. About 70%-80% of all people who get the Marburg virus died from the disease. However, the Marburg virus has not become a pandemics because most people die within three days of getting the disease. This means that the virus does not have enough time to spread a large number of people. The flu virus of 1918, on the other hand, generally took about a week to ten days to kill its victims, so it had more time to spread. While we may never be able to completely stop pandemics, we can make them less common. Doctors carefully monitor new disease that they fear could become pandemics. For example, in 2002, and 2003, doctors carefully watched SARS. Their health warming may have prevented SARS from becoming a pandemic.
8. Which of the following is mentioned as a common feature of all pandemic diseases?

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Hardly a week goes by without some advance in technology that would have seemed  incredible 50 years ago. And we can expect the rate of change to accelerate rather than slow down within our lifetime. The developments in technology are bound to have a dramatic effect on the future of work. By 2010, new technology will have revolutionized communications. People will be transmitting messages down telephone lines that previously would have been sent by post. Not only postmen but also clerks and secretaries will vanish in a paper-free society. All the routine tasks they perform. will be carried on a tiny silicon chip so that they will be as obsolete as the horse and cart after the invention of the motor car. one change will make thousands, if not millions, redundant.  Even people in traditional professions, where expert knowledge has been the key, are unlikely to escape the effects of new technology. Instead of going to a solicitor, you might go to a computer which is programmed with all the most up-to-date legal information. Doctors, too, will find that an electronic competitor will be able to carry out a much quicker and more accurate diagnosis and recommend more efficient courses of treatment. In education, teachers will be largely replaced by teaching machines far more knowledgeable than any human being. Most learning will take place in the home via video conferencing. Children will still go to school though, until another place is created where they can make friends and develop social skills.  What can we do to avoid the threat of unemployment? We shouldn’t hide our heads in the sand. Unions will try to stop change but they will be fighting a losing battle. People should get computer literate as this just might save them from professional extinction. After all, there will be a few jobs left in law, education and medicine for those few individuals who are capable of writing and programming the software of the future. Strangely enough, there will still be jobs like rubbish collection and cleaning as it is tough to programme tasks which are largely unpredictable.
5. According to the passage, in the future children ______

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Rome is the capital of Italy. This sprawling modern city has many ancient monuments. Rome’s history goes (1) __________ more than 2,500 years. Because of its age, Rome is often called the Eternal City. Rome’s many art treasures and historic buildings make the city an important center of European culture. In ancient times, Rome was the center of a (2)_________ Roman empire. The empire lasted nearly 500 years, into the ad 400s. Roman armies conquered the lands that are now Italy, Greece, Great Britain, France, and Egypt. The Romans built many roads from Rome to distant parts of their empire. This network of roads led to a saying that “All roads lead to Rome.” The Roman Empire’s influence is still present. (3) ___________ Romans spread their language, Latin, throughout Europe. Latin is the basis for Italian, French, Spanish, and other European languages. The ancient Romans were great builders. Several of their buildings still stand today. They are among Rome’s famous landmarks.The Pantheon is a temple (4)_________ to the many Roman gods of mythology. The Roman Colosseum is a four-story amphitheater. An amphitheater is like a football stadium. The Colosseum is (5)_________ Roman citizens once watched gladiators fight to the death. The Roman Forum was the political center of ancient Rome. The senate building and law courts were there, along with shops and religious buildings 

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Driving along the motorway in busy traffic, the driver suddenly presses a button on his steering wheel. The car is now driving itself. This may (1) _________________ like something from the future, but driverless cars are already in reality on California’s roads. Many cars can already park themselves on the roadside, brake automatically when the car needs to slow down, and warn the driver (2) __________ they are slipping out of the right lane, so going driverless is just the next step towards automated driving.  Driverless cars are equipped with fast broadband, allowing them to overtake other cars (3), and even communicate with traffic lights as they approach junctions. Being stuck in traffic jams could become a thing of the past, as driverless cars will be able to drive at speed (4) ___________ to each other.  More than fifty million people die or are injured in road accidents every year, and the majority of these accidents is caused by human (5) _________________. Google’s driverless car sticks of to the speed limit and doesn’t get tired. So wouldn’t it be a great idea if all cars were driverless

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Pick any day in the Piazza del Duomo in the Italian city of Pisa, and you will  undoubtedly spot a bunch of tourists posing for the same photo: hands outstretched towards the cathedral’s conspicuously tilting bell tower, as if they are supporting it with their sheer strength. The so-called Leaning Tower of Pisa is one of the most famous buildings in the world, although maybe not for the reasons its original architects would have wanted.  In 1173, construction began on a white marble bell tower for the cathedral complex in Pisa, located between the Arno and Serchio rivers in Tuscany, central Italy. By the time builders had finished the third of eight planned stories about five years later, the tower’s foundation had begun to settle unevenly on the ground beneath it, a dense mixture of clay, sand and shells. As a result, the structure had begun to tilt visibly toward the south. Shortly after that, war broke out between Pisa and Genoa, another Italian city-state, halting construction for nearly a century. This delay allowed the foundation to settle further, likely prevented the bell tower’s premature collapse.  When construction resumed, chief engineer Giovanni di Simone tried to compensate for the lean by adding extra masonry to the short side, but the additional weight caused the structure to tilt even further. The tower was officially completed around 1370, but its lean only increased over the next six centuries, becoming an integral part of the monument’s quirky appeal. Despite various attempts to reinforce it, Pisa’s tower continued to subside at a rate of some 0.05 inches per year, placing it in increasing danger of collapse. By 1990, it was leaning 5.5 degrees (or some 15 feet) from the perpendicular–the most extreme angle yet. That year, the monument was closed to visitors and the bells removed as engineers started extensive reparations to stabilize it. By siphoning earth from beneath and adding counterweights to the tower’s north end, they were able to reduce the lean to 13.5 feet, or 4.0 degrees from perpendicular. The straightening continued after the tower reopened in 2001, and in 2008 sensors showed the subsiding motion had stopped, after a total improvement of some 19 inches. Engineers now believe the Leaning Tower of Pisa will remain stable for some 200 years, barring an earthquake or other unpredictable disaster. 
5. According to paragraph 3, how was the result of Giovanni di Simone’s rectification?

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Practical experience is a must-have for today’s job seekers. According to Brazen Life’s Huffington Post article titled “Why Gaining Work Experience Is More Important Than Your Education,” many colleges and universities report that students who have completed an internship or gained work experience during their studies have higher rates of getting hired. For example, at Iowa State University, of all students who completed a co-op program to earn a BS in engineering, an astounding 90 percent got jobs after graduation. Why is practical experience so important? There are a number of reasons why you need practical work experience. First, it’s simply the smart thing to do when you’re preparing for a career in a specific field. Let’s say it’s your dream to work as a consultant for an international corporate relocation company because you love international travel and you like organizing things. So you get a part-time job working as an office assistant at a corporate relocation company… and you find out it’s very different from what you expected. In short, you realize this isn’t the job for you-and you can concentrate on finding another job where you can put your passion and skills to work, for example in the tourism industry. Alternatively, you might find out that you enjoy the corporate relocation business. That means you’re gaining invaluable industry experience that will look great on your resumé when you apply for a full-time job.  Second, practical work experience teaches valuable soft skills, such as discipline, perseverance, teamwork, leadership skills, communication skills and problem solving. Employers will look for these in candidates and they’ll want to see proof. If you’ve spent a month as a team leader at Homes for Heroes, the leadership skills, teamwork experience and problem-solving abilities you developed there can add significant value to your candidacy. Third, working helps you build your network and can provide you with contacts in your chosen field. These contacts can be extremely useful when it comes to hearing about job leads and interesting opportunities. In addition, if you’ve impressed someone, he or she might be willing to write you a letter of recommendation for a job or a place in a graduate program.  Finally, the company you’re working for might offer you a position after you’ve graduated. Your employer already knows your skills and abilities, and you’re already acquainted with the company-so it’s a win-win situation! 
6. Which of the following statements is TRUE, according to the passage?

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All students are revising carefully, for the final test is approaching soon.

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_______ is your favourite subject at school?

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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.
5. The word "its" in the second paragraph refers to the: