来源：网络 发布时间：2015-01-16 作者：上外培训网
Today, most countries in the world have canals. Even in the twentieth century, goods can be moved more cheaply by boat than by any other means of transport. Some canals, such as the Suez or the Panama, save ships weeks of time by making their voyage a thousand miles shorter. Other canals permit boats to reach cities that are not located on the coast. Still other canals drain lands where there is too much water, help to irrigate fields where there is not enough water, and furnish water power for factories and mills.
3. The size of a canal depends on the kind of boats going through it. The canal must be wide enough to permit two of the largest boat using it to pass each other easily. It must be deep enough to leave about two feet of water beneath the keel of the largest boat using the canal.
4. Some canals have sloping sides, while others have sides that are nearly vertical. Canals that are cut through rock can have nearly vertical sides. However, canals with earth banks may crumble if the angle of their sides is too steep.
5. Some canals are lined with brick, stone, or concrete to keep the water from soaking into the mud. This also permits ships to go at greater speeds, since they cannot make the banks fall in by stirring up the water. In small canals with mud banks, ships and barges must limit their speed.
6. When the canal goes through different levels of water, the ships must be raised or lowered from one level to the other. This is generally done up by means of locks. If a ship wants to go up to higher water, the lower end of the lock opens to let the boat in. Then this gate closes, and the water is let into the lock chamber from the upper level. This raises the level of the water in the lock until it is the same as the upper level of water. Now the upper gates can be opened to release the ship into the higher water. Of course there must always be enough water on the upper level to allow for the flooding of the lock.Sometimes a canal contains a series of locks when the difference in levels is very great.
7. In places where it does not rain very often, irrigation canals drain water from rivers or lakes and carry it to fields. Sometimes artificial lakes, such as the lake behind the Aswan Dam on the Nile River, provide the irrigation water.
8. In places where there is too much water, canals can drain the water off the land for use in farming. In Holland, acres and acres of land have been drained in this way. Since much of this drained land is below sea level, the water in the canals has to be pumped up to sea level. Dikes have been built in Holland to keep the sea from covering the land, as it did in the past.
9. Sometimes canals have to be built across deep valleys. Bridges or aqueducts are constructed for this purpose. The Romans often brought water to cities from great distances by building such bridges, at the top of which were canals. Some canals go through mountains by means of tunnels. One such tunnel, near Marseille, France, is over four miles long.
10. Canals existed in Egypt thousands of years ago. The great canal at Babylon, between the Tigris and Euphrates, was built about 2000 B. C.. The Grand Canal of China, which is over 900 miles long, was begun about 2,500 years ago, and took centuries to finish. During the seventeenth century, France built many canals that are still in use today. However, they are not so heavily traveled as they were a hundred years ago, before railways were built. One such canal is a short-cut between the Atlantic Ocean and the Mediterranean. In Russia, there are canals reaching from Leningrad to the Caspian Sea. Canals in Germany permit boats to go from the Black Sea to the North Sea. The Kiel Canal provides a passageway between the North Sea and the Baltic. In America, the Great Lakes are all connected by canals, enabling ships to go from the Atlantic Ocean and the St. Lawrence River to Lake Superior. Since the lakes are at different levels, they are connected by locks.
11. Many countries have built canals near the coast, and parallel to the coast. These waterways make it possible for boats to travel between ports along the coast without being exposed to the dangers of the open sea.
【点评】阅读理解第一篇选自口译阅读教程 Unit 5 Reading B “artificial waterways”。
历年中级口译考试没有出现过的现象出现了，阅读部分，没有直接采用过《阅读教程》上的篇章，而这次就这样被搬到了考场上，一方面，我们意识到出题 老师越来越 浆糊意外，也了解，随着中级口译低龄化的出现，出题老师对考生也越来越仁慈了，不管怎么样，我们老师都有要求同学回家完成教程，所以，看过书的同学一定很 开心，因为开篇，我们就捡了个大便宜。
The koala, one of Australia's most treasured creatures, is in trouble.
Faced with habitat loss, climate change and bacterial disease, koalas are being pushed into smaller and smaller regions of the country. In Queensland, the vast state in Australia's northeastern corner, surveys suggest that from 2001 to 2008, their numbers dropped as much as 45 percent in urban areas and 15 percent in bushland.
And while climate change and habitat loss are affecting many other uniquely Australian animals, too -- from birds and frogs to marsupials like wombats, wallabies and bandicoots -- it is a bacterial infection that is worrying many scientists about the fate of the koala.
''Disease is a somewhat silent killer and has the very real potential to finish koala populations in Queensland,'' said Dr. Amber Gillett, a veterinarian at the Australia Zoo Wildlife Hospital in Beerwah, Queensland.
The killer is chlamydia, a class of bacteria far better known for causing venereal disease in humans than for devastating koala populations. Recent surveys in Queensland show that chlamydia has caused symptoms in up to 50 percent of the state's wild koalas, with probably even more infected but not showing symptoms.
The bacteria -- transmitted during birth, through mating and possibly through fighting -- come in two different strains, neither the same as the human form. The first, Chlamydia pecorum, is causing a vast majority of health problems in Queensland's koalas; the second, C. pneumoniae, is less common.
Unlike C. pecorum, the pneumoniae strain can jump to other species, but so far there is no evidence that it has spread from koalas to humans or vice versa.
Chlamydia causes a host of symptoms in koalas, including eye infections, which can lead to blindness, making it difficult for them to find scarce eucalyptus leaves, their primary food source. The bacteria can also lead to respiratory infections, along with cysts that can make female koalas infertile.
The epidemic has been particularly severe in Queensland, where nearly all koalas are infected with koala retrovirus, said Dr. Gillett. This retrovirus is an H.I.V.-like infection that suppresses the koala's immune system and interferes with its ability to fight off chlamydia.
''In southern koala populations, where koala retrovirus is much less prevalent, normal immune functions tend to result in fewer cases of chlamydia,'' Dr. Gillett said.
Treating chlamydia in wild koalas is a challenge, she said. The disease is so devastating that only a small percentage of the animals can be treated successfully and returned to the wild. And infected females often become infertile -- a condition that cannot be reversed, so future population growth is affected as well.
There is no treatment available for koala retrovirus, but researchers are working to test a vaccine that would help prevent further spread of chlamydia infection in Queensland's koalas.
A study published in 2010 in The American Journal of Reproductive Immunology found that this vaccine is both safe and effective in healthy female koalas. Further work is being done to test it in koalas that are already infected.
Peter Timms, a professor of microbiology at the Queensland University of Technology who is leading the effort to test the chlamydia vaccine in koalas, is hopeful that there will be another trial this year to test the vaccine in captive male koalas, followed by wild koalas. If all goes well, plans can be set in motion to distribute the vaccine more widely.
''It's going to be impossible to vaccinate all wild koalas,'' he said.
In Australia, there is no national plan to save the koala; it is up to each region to establish management plans for its koala population. Therefore, once the vaccine is shown to be completely safe and effective, Dr. Timms suggests targeting specific, threatened populations where capturing and releasing koalas would be practical, like those bordered on all sides by housing developments and roads.
Dr. Timms is also working on a single-dose form. of the vaccine to make it more feasible to vaccinate wild koalas.Another possibility would be to make vaccine distribution a routine part of treatment for the thousands of koalas brought into care centers every year after they are injured by cars or dogs, Dr. Timms said.
While it is a combination of problems that are affecting the wild koala population, many experts believe this vaccine would be an important step in helping koalas survive longer. It may buy enough time to give researchers a chance to solve some of the other problems facing Australia's koalas.
''In situations where you combine habitat pressure, domestic dog attacks and car hits with severe chlamydial disease, the outcome for koalas is devastating,'' Dr. Gillett said.
【点评】本文出自Squeezed Into Smaller Spaces, Koalas Now Face Deadly Disease(出自：http://www.nytimes.com)，主要讨论的是由于种种因素的影响，澳大利亚的考拉现在可栖息活动的地方也越来越小，这些原因包括气候变化，疾病病毒等。考拉的死亡率也不断上升，主要因素是病毒引起的，之后作者具体分析了这种病毒，并提出了各种可行的解决方案解救考拉。