四六级阅读理解(4)

练习: Read the following passage and decide which of the choices most adequately sums up the idea of the paragraph(s) indicated. Canning Food Food which is kept too long decays because it is attacked by yeast, moulds and bacteria. The canning process, however, seals the product in a container so that no infection can reach it, and then it is sterilized by heat. Heat sterilization destroys all infections present in food inside the can. No chemical preservatives are necessary, and properly canned food does not deteriorate during storage. The principle was discovered in 1809 by a Frenchman called Nicolas Appert. He corked food lightly in wide-necked glass bottles and immersed them in a bath of hot water to drive out the air, then he hammered the corks down to seal the jars hermetically (牢牢地). Appert's discovery was rewarded by the French government because better preserved food supplies were needed for Napoleon's troops on distant campaigns. By 1814 an English manufacture had replaced Appert's glass jars with metal containers and was supplying timed vegetable soup and meat to the British navy. The next scientific improvement, in 1860,

was the result of Louis Pasteur's work on sterilization through the application of scientifically controlled heat. Today vegetables, fish, fruit, meat and beer are canned in enormous quantities. Within three generations the eating habits of millions have been revolutionized. Foods that were previously seasonal, may now be eaten at any time, and strange foods are available far from the countries where they are grown. The profitable crops many farmers now produce often depend on the proximity of a canning factory. The first stage in the canning process is the preparation of the raw food. Diseased and waste portions are thrown away; meat and fish are cleaned and trimmed; fruit and vegetables washed and graded for size. The jobs are principally done by machine. The next stage, for vegetables only, is blanching. This is immersion in very hot or boiling water for a short time to remove air and soften the vegetable. This makes it easier to pack into cans for sterilization. Some packing machines fill up to 400 cans a minute. Fruit, fish and meat are packed raw and cold into cans, and then all the air is removed. When the cans are sealed, the pressure inside each can is only about half the pressure of the outside air. This is 'vacuum' packing. During the sterilization process which follows, the cans are subjected to steam or boiling water, with the temperature and duration varying according to the type of food. Cans of fruit, for example, take only 5-10 minutes in boiling water, while meat and fish are cooked at higher temperatures for longer period. After sterilization, the cans are cooled quickly to 32℃ to prevent the contents from becoming too soft. The final stage before dispatch (发送) to the wholesale or retail grocer is labeling, and packing the tins into boxes. Nowadays, however, labeling is often printed on in advance by the can-maker and no paper labels are then required. 1. The main idea of Para.1 is A) Food scientifically sealed in cans is safe from decay. B) Sterilization -- the key to the

safe-keeping of food. C) The use of chemicals in preventing the decay of food. 2. The main idea of Paras. 2 and 3 is A) The history and early methods of preserving food. B) The French influence in food canning. C) The scientific principles of food canning. 3. The main idea of Para. 4 is A) How the canning industry affects our lines. B) The economic effects of the canning industry. C) The range and diverse advantages of canned food. 4. The main idea of Paras. 5-8 is A) The mechanical miracle of food canning. B) The step-by-step modern processes of canning food. C) The process of preparing, washing and grading food for canning.

KEY: A, A, C, B

练习Passage two::::::: America is a country on the move. In unheard of numbers, people of all ages are exercising their way to better health. According to the latest figures, 59 percent of American adults exercise regularly-up 12 percent from just two years ago and more than double the figure of 25 year ago. Even non-exercises believe they would be more attractive and confident if they were more active. It is hard not to get the message. The virtues of physical fitness are shown on magazine covers, postage stamps, and television ads for everything from beauty soaps to travel books. Exercise as a part of daily life did not catch on until the late 1960s when research by military doctors began to show the health benefits of doing regular physical exercises. Growing publicity (宣传) for races held in American cities helped fuel a strong interest in the ancient sport of running. Although running has leveled off in recent years as Americans have discovered equally rewarding-and sometimes safer-forms of exercise, such as walking and swimming, running remains the most popular form of exercise. As the popularity of exercise continues to mount, so does scientific evidence of its health benefits. The key to fitness is exercising the major muscle groups vigorously (强有力地) enough to approximately double the

heart rate and keep it doubled for 20 to 30 minutes at a time. Doing such physical exercises three times or more a week will produce considerable improvements in physical health in about three months. 6. According to the passage, what was the percentage of American adults doing regular physical exercises two years ago? A) About 70%. B) Nearly 60%. C) Almost 50%. D) More than 12%. 7. A growing interest in sports developed after . A) research showed their health benefits B) people got the message from magazine covers and postage stamps C) scientific evidence of health benefits was shown on TV ads D) an increasing number of races were held in American cities 8. Which of the followin …… 此处隐藏：9482字，全部文档内容请下载后查看。喜欢就下载吧 ……