Read the article and select the best answer. Article: Sustainable development is applied to just about everything from energy to clean water and economic growth, and as a result it has become difficult to question either the basic assumptions behind it or the way the concept is put to use. This is especially true in agriculture, where sustainable development is often taken as the measure of progress without a proper appreciation of historical and cultural perspectives. To start with, it is important to remember that the nature of agriculture has changed markedly throughout history, and will continue to do so. Medieval agriculture in northern Europe fed, clothed and sheltered a mainly rural society with a much lower population density than it is today. It had minimal effect on biodiversity, and any pollution it caused was typically localized. In terms of energy use and the nutrients captured in the product it was relatively inefficient. Contrast this with farming since the start of the industrial revolution. Competition from overseas led farmers to specialize and increase yields. Throughout this period food became cheaper, safer and more reliable. However, these changes have also led to habitat loss and to reducing biodiversity. All this means that agriculture in the 21st century will have to be very different from how it was in the 20th. This will require thorough thinking. For example, we need to move away from the idea that traditional practices are certainly more sustainable than new ones. We also need to abandon the notion that agriculture can be "zero impact". The key will be to abandon the rather simple and static measures of sustainability, which centre on the need to maintain production without increasing damage. Instead we need a more dynamic interpretation, one that looks at the pros and cons of all the various way land is used. There are many different ways to measure agricultural performance besides food yield: energy use, environmental costs, water purity, carbon footprint and biodiversity. It is clear, for example, that the carbon of transporting... Question: What will agriculture be like in the 21st century? Options: A: It will abandon traditional farming practices B: It will mainly keep traditional farming C: It will go through complete changes D: It will cause zero damage to the environment
C

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Read the article and select the best answer. Article: MOOCs, an acronym for "massive open online courses," mark an important, possibly revolutionary, development in education. These courses are online, free of charge, and open to anyone in the world who has a laptop and an Internet connection. Moreover, they are mainly offered by elite universities like Standford, Berkeley, Harvard and Columbia. The courses, like normal college courses, are sequenced by difficulty, enabling students to progress from beginners to the advanced. The courses cover not only a broad range of technical subjects such as math and computer science, but also courses in the social sciences and the humanities . Though MOOCs are not offered for credit and degree, many students enroll in the courses for real skills or knowledge which they can put to some practical use. Some students even form online study groups, or in-person groups with students who live nearby. The format seems superior to the traditional school class. The average quality of the lecturer is much higher, because students do not have to stick with a mediocre lecturer. Besides, students can scroll back or forward--in short, they can go at their own learning speed, which they cannot do in a live lecture. And, of great importance, they do not have to travel anywhere to attend an online lecture. One can obtain a first-class American college education wherever he or she lives and however little money he or she has. There is a problem of asking questions of the lecturer in a class of ten thousand students, but some MOOCs have solved it by allowing students to post questions online for a vote, and only the most popular questions are put to the lecturer. In a knowledge era, lifelong learning is not confined to a traditional classroom. Of course, students enrolling in MOOCs cannot be compared with those who are in traditional universities, but we need to rethink what a "students" is. Students in MOOCs are very clever, have work experience, and in many cases, have already developed a set of core competences. Moreover, they also offer... Question: Students enroll in MOOCs mainly for _ . Options: A: credits B: degrees C: skills D: study groups
(Answer)
C

Read the article and select the best answer. Article: We all know that eating junk food can make us fat. However, a new study suggests that it can do more than that - it can also make us lazy, reported CBS News. In the study, researchers at the University of California, Los Angeles, US divided 32 female rats into two groups. The first group was fed a diet of healthy food such as corn and fish, while the second was given a diet of highly processed food rich in sugar, namely "junk food". Within three months, the rats in the second group were already much fatter than those on the healthy diet. And when researchers trained the rats to do simple tasks, they found even more differences between the two groups rather than weight. During the task - pushing a lever to receive a reward of sugar water - the rats on the junk food diet were found to be less willing to move, and they took longer breaks between each push than the lean rats did. "It is as if the rat is thinking 'This is too much work'," Aaron Blaisdell, leader of the study, told the Los Angeles Times. But what about the possibility that the fat rats were less passionate about getting sugar water because they were already eating lots of sugar in their daily diet? That's why researchers repeated the tests by rewarding fat rats with plain water when they were extremely thirsty. However, the results came out just the same. According to researchers, these differences suggest that junk food changed the chemistry in the rats' brains. The experiment didn't end _ . After six months, the rats' diets were switched, and the overweight rats were given a healthy diet for nine days. However, this change didn't help reduce their weight or improve their ability to perform tasks, which means the effects of their junk food diet persisted . "There's no quick fix," said Blaisdell. For a long time, we've believed that people become fat because they are lazy. But this study has proven the opposite to be true as well, which indicates that laziness and obesity are a "vicious cycle ". So, if you constantly feel tired, lacking any... Question: During the first three months of the experiment by researchers at the University of California, _ . Options: A: rats from the healthy diet group ate nothing but corn and fish B: rats on the junk food diet ate more than those on healthy diet C: rats on the healthy food diet performed better at simple tasks than those on the junk food diet D: rats on the junk food diet seemed uninterested in sugary food
C