新视野大学英语第二版第三层第二单元试题答案

Part 2 Understanding Long Conversations(每小题：1 分)Directions: In this section you'll hear a long conversation or conversations. Listen carefully and choose the best answer to the questions you hear.Questions 1 to 5 are based on the same passage or dialog.Part 5 Cloze (with four choices provided)(每小题：1 分)Directions: Read the following passage carefully and choose the best answer from the four choices given for each blank. Questions 1 to 20 are based on the following passage.Part 6 Skimming and Scanning (Multiple Choice + Blank Filling)(每小题：1 分)Directions: Read the following passage and then answer the questions. For questions 1-7, choose the best answer from thefour choices marked A, B, C and D. For questions 8-10, complete the sentences with the information given in the passage.Questions 1 to 10 are based on the same passage or dialog.Engineers of the WoodsIn the forests of North America, where the winters are often long and cold, small lakes can be found along the streams. Sometimes these lakes are natural, sometimes they are man-made, and sometimes they are the constructions of beavers (海狸). You can tell a beaver lake by its dam. To make the dams, the beavers lay sticks and branches on top of each other to form an effective barrier against the water of the stream. Near the dam the beavers lay sticks and branches. Usually this barrier is similar to a small island in a lake. This is the house where a beaver family spends the winter, protecting themselves from enemies and from the cold. The beavers are able to keep dry in the center of the house, which is above water level.The beavers work hard to make their house. They cut down trees, gather branches and put them together with mud. Most of the summer is spent on this kind of work, but in winter the beavers' work pays off. Their house protects them from bears as well as the cold.The beaver is related to animals such as rats and mice. The beaver, however, is much bigger than his relatives. An adult beaver may weigh more than 50 pounds, and his body may be about three feet long. His tail will add ten to twelve more inches to his length. His back feet are webbed, which help him swim rapidly. His front feet are similar to a pair of strong hands. With them he can carry wood and stones. His eyes, nose and ears are small, but he has two huge front teeth. These teeth are always growing, and he must keep them sharp by constant use. The teeth of an adult beaver are yellow from the bark of trees that he bites.Men attach great value to the beaver because beavers can be sold to make expensive clothing. Beavers have almost disappeared from Europe because trappers (设阱捕兽者) have killed so many of them. Beavers might easily have become extinct in America, too, but laws were passed to protect them before they were all killed.The beaver likes family life, and lives with the same mate allhis life. Several young—usually two to five—are born every year. The little beavers stay with their parents for two years before mating and setting out on their own. They share the work of building dams, constructing homes and raising the young.When there are too many beavers in one place, some of them will group together in another place. They usually choose a spot near some fairly deep lake or river, where there are trees. The bark of trees is eaten as food. Then the wood is used for building.Sometimes the lodges are built on the bank of the water, but usually they are built on an island in the water. If there is no island already there, the beavers make one by piling sticks and mud on the bed of the river until the top is a few inches above the level of the water. The top is carpeted with small pieces of wood leaves. A roof of sticks and lots of mud is then built over this "floor". Food for the winter is taken to the lodge before the weather gets too cold. Some of it—the larger pieces—is stored on the bottom of the lake or river, near the entrance to a tunnel leading up to the lodge. There are sometimes several such entrances, under the surface of the water. Wood that is kept under water may be stuck in the mud, or weighted down with stones.Beavers prefer to work at night. One beaver, on a single night, can cut down a tree that is eight inches around. After cutting down the tree, the beaver cuts the trunk into pieces that can be carried. He uses these as the base for the dam. A small dam may be enlarged after several years, in order to flood a large surface and provide living space for more beavers. Under favorable conditions, a dam may last for a hundred years or more. Naturally, other animals use these dams as bridges, forcing the beavers to keep the dams in good repair. The dams must be strong enough to hold up against the pressure of ice in spring and sometimes, holes are made by the beavers, after heavy rains, to allow excess water to run off.Another type of work beavers do is canal digging. When they have used up the good trees near their home, they must bring more wood from farther away. To accomplish this, they may dig a canal (运河) to float the trees to the place where they are needed.Beaver dams help people because they prevent floods and bring water to farms. It is fortunate that these animals have not been allowed to disappear completely.Part 8 Reading Comprehension (MultipleChoice)(每小题：1 分)Directions: Read the following passages carefully and choosethe best answer from the four choices marked A, B, C and D. Questions 1 to 5 are based on the same passage or dialog.Summer is the ideal time of year for one of my favorite outdoor activities, hiking (徒步旅行). It is much more than just a great workout. You get to be outside of the confines of a gym and be together with nature. You breathe in the fresh, clean air while the city life you endured all week just fades away. You are suddenly transported somewhere else. You are suddenly in a place where you can appreciate the untouched, simplistic beauty of nature. The trees are green, the wild flowers are growing and the woods are filled withactivity. Once you experience it, you're hooked.Whether hiking in the deserts of Arizona or the mountains of Alberta, you suddenly realize you are not alone and there is something much bigger at work. There is a realization that life is precious and you think deeply about your life.Another wonderful part of hiking is that you can participate at any level and it is, for the most part, free. It is a great way to escape the rat race, even during the week. If you have any problems you need to solve, hiking is really good for clearing your head and removing stress.If hiking sounds intimidating to you, it is essentially walking on a whole new level. Experts have spoken about the benefits of walking for years. Walking doesn't stress your legs as much as running and countless studies agree walking leads to weight loss and better health. It is good for your heart, reduces illness and has even been shown to enhance your thinking. So why wouldn't you want to do it?Questions 6 to 10 are based on the same passage or dialog. Another example of the dangers of a restricted diet may be seen in the disease known as "beri-beri" (脚气病), which used to affect large numbers of Eastern peoples who lived mainly on rice. In the early years of the 20th century, a Dutch scientist named Eijkman was trying to discover the cause of beri-beri. At first he thought it was transmitted (传送) by a germ (细菌). He was working in a Japanese hospital, where the patients were fed on rice which had had the external husk (壳) removed from the grain, called "white rice." It was thought this would be easier for weak, sick people to digest.Eijkman thought his germ theory was confirmed when he noticed the chickens in the hospital yard, which were fed on scraps (碎片)from the patients' plates, were also showing signs of the disease. He then tried to isolate the germ he thought was causing the disease, but his experiments were interrupted by a hospital official, who ruled that the huskless polished rice was too good for chickens. The chickens should be fed cheap rice with the external covering still on the grain, called "brown rice."Eijkman noticed that the chickens began to recover on the new diet. He began to consider the possibility that eating brown rice somehow prevented or cured beri-beri—even that a lack of some ingredient in the husk might be the cause of the disease. Indeed this was the case. The element needed to prevent beri-beri was shortly afterwards isolated from rice husks and is now known as Vitamin B. The white rice, though more expensive, was keeping alive the disease the hospital was trying to cure.Questions 11 to 15 are based on the same passage or dialog.A strict vegetarian is a person who never in his life eats anything derived from animals. The main objection to vegetarianism (素食主义) on a long-term basis is the difficulty of getting enough protein—the body-building element in food. If you have ever been without meat or other animal foods for some days or weeks (say, for religious reasons) you will have noticed that you tend to get rather weak physically. You are glad when the fast (禁食) is over and you get your reward of a delicious meat meal.Proteins are built up from about twenty food elements called "amino acids" (氨基酸), which are found in greater amounts in animal protein than in vegetable protein. This means you have to eat a great deal more vegetable than animal food in order to get enoughof these amino acids. A great deal of the vegetable food goes to waste in this process and from the physiological (生理学的) point of view there is not much to be said in favor of life-long vegetarianism.The economic side of the question, though, must be considered. Vegetable food is much cheaper than animal food. However, since only a small proportion of the vegetable protein is useful forbody-building purposes, a consistent vegetarian, if he is to gain the necessary 70 grams (克) of protein a day, has to consume a greater bulk of food than his digestive organs can comfortably deal with. In fairness, though, it must be pointed out that vegetarians claim they need far less than 70 grams of protein a day.Questions 16 to 20 are based on the same passage or dialog. Whether or not vegetarianism should be advocated for adults, it is definitely unsatisfactory for growing children, who need moreprotein than they can get from vegetable sources. Alacto-vegetarian (part milk, part vegetable) diet, which includes milk and milk products such as cheese, can, however, be satisfactory as long as enough milk and milk products are consumed.Meat and cheese are the best sources of usable animal protein and next come milk, fish and eggs.Slow and careful cooking of meat makes it more digestible and assists in the breaking down of the protein content by the body. When cooking vegetables, however, the vitamins, and in particular the water-soluble (溶解于水的) Vitamin C, should not be lost through over-cooking.With fruit, vitamin loss is too small to be important, because the cooking water is normally eaten along with the fruit, and natural chemicals in the fruit help to hold in the vitamin C.Most nutrition (营养) experts today would recommend a balanced diet containing elements of all foods, largely because of our need for sufficient vitamins. Vitamins were first called "added food factors" when they were discovered in 1906. Most foods contain these other substances necessary for health, in addition to carbohydrates (碳水化合物), fats, minerals and water. The most common deficiency in Western diets today is lack of vitamins. The answer is variety in food. A well-balanced diet, having sufficient amounts of milk, fruit, vegetables, eggs, and meat, fish or chicken (i.e. any good protein source), usually provides the minimum daily requirement of all the vitamins.。