.

     Scientific experiments can sometimes go wrong and when they do, the results may range from the disastrous to the troubling. One such experiment took place in South America about fifty years ago. Whether its final consequences will cause serious damage or nothing more than a small trouble still remains to be seen.

       The story began in 1956 when an American scientist working in Brazil decided to solve the problem of increasing the productivity of that country’s bees. He imported a very active type of African bee from Tanzania and mated (交配) it with the more easygoing native variety to produce a new kind of bees. The new bees worked harder and produced twice as much honey. It seemed that Professor Kerr, for that was the scientist’s name, had a total success on his hands.

       Then things began to go wrong. For some reason as yet unseen, but perhaps as a result of something in their environment, the new bees began to develop extremely attacking personalities. They became bad-tempered and easy to be angry, attacked the native bees and drove them from their living places.

       But worse was to follow. Having taken over the countryside, the new bees, with their dangerous stings (叮) , began to attack its neighbors—cats , dogs, horses, chickens and finally man himself. A long period of terror began that has so far killed a great number of animals and about 150 human beings.

       This would have been enough if the bees had stayed in Brazil. But now they are on the move, heading northwards in countless millions towards Central and North America, and moving at the alarming speed of 200 miles a year. The countries that lie in their path are naturally worried because it looks as if nothing can be done to stop them.

60. Which of the following statements is right?

A. The results of the South American experiment have caused a serious trouble.             

B. Scientific experiments in South America have proved to be wrong.

C. The results of the South American experiment are not yet certain.                     

D. It’s clear that scientific experiments in South America are not important.

61. The experiment mentioned in this passage was designed to _________.

       A. increase the amount of honey in Brazil

       B. make Brazilian bees more easy-going

       C. increase the number of bees in Brazil

       D. make African bees less active

62. Which of the following may be the cause of the new bees attacking personalities?

       A. Their production of honey.          B. Their hard work.

       C. Their living environment.                D. Their bad temper.

63. The last paragraph implies that __________.

       A. the bees have been driven to Central and North America

       B. The bees may bring about trouble in more countries

       C. the bees must be stopped from moving north

       D. the bees prefer to live in Brazil

.

Centuries ago, man discovered that removing moisture (湿度,水分) from food helps to store it, and that the easiest way to do this is to expose the food to sun and wind.

All foods including water—cabbage and other leaf vegetables contains as much as 93% water, potatoes and other root vegetables 80%, lean (瘦的) meat 75% and fish, anything from 80% to 60%, depending on how fatty it is.If this water is removed, the activity of the bacteria which cause food to go bad is controlled.

Nowadays most foods are dried mechanically.The conventional method of such dehydration (脱水) is to put food in chambers (室) through which hot air is blown at temperature of about 110℃ at entry to about 43℃ at exit.This is the usual method for drying such things as vegetables, mincemeat and fish.

Liquids such as milk, coffee, tea, soups and eggs may be dried by pouring them over a heated steel cylinder (圆筒), then put them into a chamber through which a current of hot air passes.In the first process, the dried material comes off the roller as a thin film which is then broken up into small, though still relatively flakes (薄片).In the second process it falls to the bottom of the chamber as small powder.Where recognizable pieces of meat and vegetables are required, as in soup, the ingredients (成分) are dried separately and then mixed.

Dried foods take up less room and weigh less than the same food packed in cans or frozen, and they do not need to be stored in special conditions.For these reasons they are convenient to the climbers, explorers and soldiers in battle, who have little storage space.They are also popular with housewives because it takes so little time to cook them.

64.It can be inferred from the passage that _______________________.

       A.the fattier fish contain as much water as the lean one

       B.the fattier the fish is, the more water it may contain

       C.a fatty fish holds less water than a lean one

       D.the water content of fish has nothing to do with the content of their fat

65.The underlined word “conventional” in Paragraph 3 can most probably be replaced by _______.

       A.particular  B.scientific   C.usual D.special

66.Which of the following statements is NOT TRUE about drying food?

       A.The removal of water in food helps prevent it from going rotten.

       B.The open-air method of drying food has been known for hundreds of years.

       C.In the course of dehydration, the temperature of hot current coming from entry to exit is gradually going up.

       D.The process of drying liquids is much more complex than that of drying solid food.

67.The last paragraph mainly talks about ____________________.

       A.the reason why housewives like dried food          

       B.the general convenience of dried food

   C.the methods of storing food                                 

       D.the advantages of dried, canned and frozen food

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