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The Development of RubberHere is the story of rubber. From the earliest time it was common knowledge (51) the Peruvians that when a cut was made in the outside skin of a rubber tree, a white liquid (52) milk came out, and that (53) this a sticky (粘的) mass of rubber might be made. This rubber is soft when warm, so that it is possible to give it any (54) . The Peruvians made the (55) that it was very good for keeping out the wet. Then in the early 1800’s, the Americans made use of it for the first time. First they made overshoes to (56) their feet dry. Then came a certain Mr. Mackintosh, who made coats of cloth covered with natural rubber. From that day to this we have been coating cloth with rubber as Mr. Mackintosh (57) , and our raincoats are still named after him.But these first rubber overshoes and raincoats were all soft and sticky in summer, and (58) and inelastic (无弹性的) in the winter when it was col D. But the rubber we have today is soft and elastic (有弹性的), (59) very strong m even in the warmest summer and the coldest winter. This was made (60) by a man called Goodyear. After many (61) , he found that nitric acid (硝酸) made the rubber much better, but it is not hard and strong enough. Then a strange thing took(62) . A friend of his, Nicholas Hayward, had the idea in his sleep that rubber might be made hard and strong if mixed with sulfur (硫磺) and put in the sun. Goodyear put this idea (63) the test, and saw that it did have more or less the desired effect though somewhat less than more. The only effect it had was on the outside of the rubber. It is common knowledge now that the (64) to make rubber hard and strong is by heating it with sulfur. It took Goodyear four more years to find this metho D. When at last he did it, he had (65) at all. Everything of the smallest value had been used to get money, even his sons’ school-books. 52（）
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The Supercomputer Network1 Recently, ten laboratories run by governments in different parts of the world have become linked. Their computers have been connected so they can "talk" to each other. This may not seem very dramatic news, but it Is the beginning of a development that will Increase the power of the Internet tremendously.2 The Internet Is an Interconnected (互联) system of networks that connects computers round the world and facilitates the transmission and exchange of information. The way that you use the Internet is by accessing this network. This depends on the power that your system allows you to use. The power of your computer is responsible for how fast you can download (下载) files, how much data you can store, etc. If your computer is old and slow, accessing the information can be very difficult.3 The new development in information technology has been called "the grid" (网格技术), and it will be a network of computers that are linked together. The "grid" will work in a different way from the Internet, enabling you to get the power of the biggest computers in the world on your computer. Accessing the information will no longer depend on the power of your computer. The idea is that while you access information, you will also have access to the power of the bigger computer stations.4 One advantage of this revolutionary idea is that geographical location will become irrelevant. The "grid" will decide which are the best parts of a worldwide network to do the job you want. This means that you may be accessing a computer in Japan to solve a problem in Alaska.5 The "grid" can be compared to having an efficient personal assistant. You can give your assistant a task and "he" will do it for you. The assistant will do the preliminary research, collect the data, compare them and decide on the best course of action by accessing any of the computer centres in the "grid" that happen to have the relevant information. All you have to do is assign the task, sit back and wait.6 At present, possible applications of the "grid" in scientific research are being explored While It has taken about fifteen years for Internet use to become widespread, experts believe that the "grid" could be up and running for private individuals far more quickly. Scientists working on "grid" projects are convinced that it will be as widely used as the web in the next ten years. Paragraph 4 ______
The Development of RubberHere is the story of rubber. From the earliest time it was common knowledge (51) the Peruvians that when a cut was made in the outside skin of a rubber tree, a white liquid (52) milk came out, and that (53) this a sticky (粘的) mass of rubber might be made. This rubber is soft when warm, so that it is possible to give it any (54) . The Peruvians made the (55) that it was very good for keeping out the wet. Then in the early 1800’s, the Americans made use of it for the first time. First they made overshoes to (56) their feet dry. Then came a certain Mr. Mackintosh, who made coats of cloth covered with natural rubber. From that day to this we have been coating cloth with rubber as Mr. Mackintosh (57) , and our raincoats are still named after him.But these first rubber overshoes and raincoats were all soft and sticky in summer, and (58) and inelastic (无弹性的) in the winter when it was col D. But the rubber we have today is soft and elastic (有弹性的), (59) very strong m even in the warmest summer and the coldest winter. This was made (60) by a man called Goodyear. After many (61) , he found that nitric acid (硝酸) made the rubber much better, but it is not hard and strong enough. Then a strange thing took(62) . A friend of his, Nicholas Hayward, had the idea in his sleep that rubber might be made hard and strong if mixed with sulfur (硫磺) and put in the sun. Goodyear put this idea (63) the test, and saw that it did have more or less the desired effect though somewhat less than more. The only effect it had was on the outside of the rubber. It is common knowledge now that the (64) to make rubber hard and strong is by heating it with sulfur. It took Goodyear four more years to find this metho D. When at last he did it, he had (65) at all. Everything of the smallest value had been used to get money, even his sons’ school-books. 54（）
Birdsong A male zebra finch chirps away to himself. Suddenly he notices a female bird nearby. He realizes he has an audience and immediately changes his song. Can the female tell the difference in his performance According to a new study, the female zebra finch knows. And she prefers the special trills he creates when he sings to her. A male zebra finch changes his song when singing to a female in ways that people can barely detect. But the female finch can tell the difference. Scientists had noticed slight variations in the songs of male zebra finches based on whether they were singing alone or whether there was a female (and potential mate) nearby. With an audience, the males sped up the pace of their songs and controlled the notes they used. For this study, researchers Sarah C. Woolley and Allison Doupe at the University of California, San Francisco decided to focus attention on the listening females, which have not been well studied in the past. In the study, Woolley and Doupe set up, a long cage with a sound speaker at each end. One broadcast the sound of a male zebra finch singing to himself, like someone singing in the shower. The other speaker broadcast a male performing for a female audience, as if he was giving a concert. Female birds were placed between the two speakers. Some of the birds had mates, others didn’t. The females shifted around a bit, and then most of them hopped over to sit beside just one speaker. All the birds that made a clear choice liked songs meant for a female audience, even if they’d never met the male. Mated females also had a chance to listen to two different performance songs, one from an unknown male, and one from their mate. They spent more time listening to the concert version of their mates’ songs. This suggests that after a while, females learn to recognize and prefer the songs of their mates. Scientists then studied the brains of the females. They found certain areas of the brain perked up when the birds listened to the concert songs. These brain areas may be involved in recognizing and evaluating the songs, and storing the memories of them. This research deals with what’s called directed communication, when the communicator, or sender, focuses the message for a specific audience. One example is the way moms speak to their babies. Mothers around the world use the same sort of high-pitched sing-song chatter, and the babies respond best to those sounds. Songbirds are one of the only other species known to learn their communication, in this case their songs. What is meant by "concert songs" in the seventh paragraph
Doubts and Debates over the Worth of MBA Bill Gates, the billionaire Microsoft chairman without a single earned university degree, is by his success raising new doubts about the worth of the business world’s favorite academic title: the MBA ( Master of Business Administration). The MBA, a 20th-century product always has borne the mark of lowly commerce and greed (贪婪) on the tree-lined campuses ruled by purer disciplines such as philosophy and literature. But even with the recession apparently cutting into the hiring of business school graduates, about 79,000 people are expected to receive MBAs in 1993. This is nearly 16 times the number of business graduates in 1960, a testimony to the widespread assumption that the MBA is vital for young men and women who want to run companies some day. "If you are going into the corporate world it is still a disadvantage not to have one," said Donald Morrison, professor of marketing and management science. "But in the last five years or so, when someone says, ’ Should I attempt to get an MBA,’ the answer a lot more is: It depends. " The success of Bill Gates and other non-MBAs, such as the late Sam Walton of Wal-Mart Stores Inc. has helped inspire self-conscious debates on business school campuses over the worth of a business degree and whether management skills can be taught. The Harvard Business Review printed a lively, fictional exchange of letters to dramatize complaints about business degree holders. The article called MBA hires "extremely disappointing" and said "MBAs wants to move up too fast, they don’t understand politics and people, and they aren’t able to function as part of a team until their third year. But by then, they’re out looking for other jobs. " The problem, most participants in the debate acknowledge, is that the MBA has acquired an aura (光环) of future riches and power for beyond its actual importance and usefulness. Enrollment in business schools exploded in the 1970s and 1980s and created the assumption that no one who pursued a business career could do with out one. The growth was fueled by a backlash (反冲) against the anti-business values of the 1960s and by the women’s movement. Business people who have hired or worked with MBAs say those with the degrees often know how to analyze systems but are not so skillful at motivating people. "They don’t get a lot of grounding in the people side of the business," said James Shaffer, vice president and principal of the Towers Perrin management consulting firm. From the passage we know that most MBAs______.
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