题目内容
One of the advantages of chain schools is that they are famous all over the world.
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听力原文： Mr. Johnson was born in a little village near the coast and went to school in the nearest seaside town, but he was not a lover of the sea. Even when walking along the sands, he was afraid of being cut off by the tide. Mr. Johnson was not a very good swimmer, so perhaps this was why he disliked the sea.
After working for some years in London, Mr. Johnson was transferred to a town near the coast and, of course, the family often made trips to the beach. One day his children asked him to take them out into the bay in a boat. The sun shone brightly. There was little wind and the water was calm. So Mr. Johnson hired a boat and rowed out into the bay with his two children. They went farther than they had intended, past the cliff and out into the open sea. At first all went well, but when they decided to turn back they found themselves faced with difficulties. A strong wind had sprung up and the currents were rather dangerous.
Mr. Johnson rowed hard, but it seemed they were making little progress. The children were waving to attract the attention of the people on the beach. Just then a motor-boat appeared from the direction of the bay. Their trouble had been noticed and the motor-boat had come to their rescue. A rope was soon attached and their boat was pulled back round the cliff to the shore.
Mr. Johnson's dislike of the sea became even stronger after the experience.
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Chains don't offer students the chance to pursue their study from one country to another.
听力原文： I want to talk today about some studies. They seem to indicate that there is a startling world-wide decline in the number of amphibians, such as flogs, toads and salamanders. There's little doubt that one reason why the number of amphibians is declining is their habitats have been destroyed when the developers fill in ponds and marshes to build houses. Amphibians can't just move somewhere. They need water to lay their eggs in. Another problem is the growing fish industry. Another range of popular pool fish such as carp have been introduced to many lakes and ponds all over the world. Raising and selling these fish can be profitable, but the fish eat the eggs and offspring of amphibians that were already living in the lakes and ponds. Other factors could be contributing to the decline include acid rain and the spread of pesticide residues. Many pesticides that farmers added to their crops are eventually washed away bythe rain and end upin pondsand other bodies of water where amphibians live. Amphibians are especially vulnerable to pesticides dissolved in the water because of their moist skins. Water can pass through amphibians allowing toxins dissolved in the water to enter the amphibians'body.
What does the speaker mainly discuss？
Why is such a basic health service so easily knocked out？ Mainly because private companies have had little incentive to pursue it. To create a single dose of flu vaccine, a manufacturer has to grow live virus in a 2-week-old fertilized chicken egg, then crack the egg, harvest the virus and extract the proteins used to provoke an immune response. Profit margins are narrow, demand is fickle and, because each year's flu virus is different, any leftover vaccine goes to waste. As a result, the United States now has only two major suppliers (Chiron and Aventis Pasteur)--and when one of them runs into trouble, there isn' t much the other can do about it. "A vaccine maker can't just call up and order 40 million more fertilized eggs," says Manon Cox, of Connecticut-based Protein Sciences Corp. "There's a whole industry that's scheduled to produce a certain number of eggs at a certain time. "
Sleeker technologies are now in the works, and experts are hoping that this year's fiasco will speed the pace of innovation. The main challenge is to shift production from eggs into cell cultures--a medium already used to make most other vaccines. Flu vaccines are harder than most to produce this way, but several biotech companies are now pursuing this strategy, and one culture-based product (Solvay Pharmaceuticals' Invivac) has been cleared for marketing in Europe.
For Americans, the immediate challenge is to make the most of a limited supply. The government estimates that 95 million people still qualify for shots under the voluntary restrictions announced last week. That' s nearly twice the number of doses that clinics will have on hand, but only 60 million Americans seek out shots in a normal year. In fact, many experts are hoping the shortage will serve as an awareness campaign--encouraging the people who really need a flu shot to get one.
Shortages of flue vaccine show that ______.
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