78. In the writer's eyes, computers　　　　　　　　 .

A. are too expensive for small farmers

B. can be a valuable tool for the farmer　

C. can be used to help oranges grow bigger

D. cannot take the place of the farmer's experience and judgement

77. Ed tried to protect his crop by　　　　　　　　 .

A. using a wind machine to　 drive away the cold air

B. equipping his orange trees with a computer

C. watering it at the proper time

D. picking his fruit at the first sign of frost

76. The passage is mainly about　　　　　　　　 .

A. a farmer's expert care for his orange trees

B. the different uses of computers

C. growing oranges in Florida's changeable weather

D. different ways of frost protection

75. The passage is mainly about　　　　　　　 　　.

A. a group of cold-water swimming lovers

B. the Polar Bears' life in New York

C. doctors' ideas about cold-water swimming

D. the requirements of the Polar Bear Club

(C)

Farmer Ed Rawlings smiles as he looks at his orange trees. The young oranges are growing well in Florida's weather. Warm sunshine and gentle rains, along with Ed Rawlings'expert care, will produce a good crop of oranges this year.

But Ed has to fight against Florida's changeable winter weather. In January and February, temperatures can destroy Ed's entire orange, crop. Having farmed in Florida for the past 35 years, Ed Rawlings is prepared for the frosts(霜). When temperatures drop below freezing， Ed tries to save his crop by watering his orange trees. The water freezes and forms a thin layer (层)of ice on the trees. Strange as it may sound, this thin layer of ice actually keeps the fruit warm.

What happens is simple. When the trees are watered, the water loses heat and becomes ice. The warmth of the heat it loses is sucked in by the fruit and keeps its temperature at a safe level. Ed Rawlings has effectively used this method(方法)to save many orange crops.

But Ed still faces some difficulties. The trees should be watered at the exact moment the temperature drops to the freezing point. Also, just the right quantity of water must be used. Too much water can form a thick layer of ice that will break the trees'branches. Another difficulty is that wind blows away the heat. So Ed has to worry about not only when but also how often his trees should be watered, and how much water should be used.

Computer technology may help Ed Rawlings with some of these worries. With equipment, air and soil temperatures and wind speed can be measured. The information is fed into a computer which can tell when temperatures drop to freezing. The computer can correctly decide the quantity of water to be used and how frequently the trees should be　　 watered. Ed Rawlings will find looking after his orange trees a lot easier with the help of a computer, and we'll all have the benefits(or advantages)of computer-age oranges.

74. The Polar Bears like to swim all the year round,for　　　　　　　　　 .

A. they can remain young

B. it is an easy way to keep the body warm in winter

C. they find it enjoyable and interesting

D. they might meet fewer troubles in life

73. According to the passage, some doctors believe it is true that　　　　　　　　　 .

A. you are healthy if cold-water swimming turns your skin color blue

B. cold-water swimming causes more heart attacks in summer than in winter

C. cold-water swimming can make the body temperature dangerously high

D. Polar Bears are bears swimming in freezing water

72. Doctors　　　　　　　　　　　　 .

A. encourage people to take part in cold-water swimming actively

B. point out the possible danger of blood illness during cold-water swimming

C. believe swimming is helpful both in winter and in summer

D. have different ideas about the medical effects of cold-water swimming

71. The members of the Polar Bear Club must meet the following requirements except that　　　　　　　　　 .

A. they should be easy to make friends with

B. they must swim outdoors at least 8 times in the four cold months

C. they must agree to swim outdoors from November through February

D. they must reach the age of 60

70. After experiencing the American school life,Mike thought　　　　　　　

A.a better education should include something good from both America and Germany

B.German schools trained students to be better citizens

C.American schools were not as good as German schools

D. the easy life in the American school was more helpful to students

(B)

When did you last see a polar bear(北极熊)?On a trip to a zoo, perhaps?If you had attended a winter activity in New York a few years ago, you would have seen a whole polar bear club. These "Polar Bears" are people who meet frequently in the winter to swim in freezing cold water.That day, the air temperature was 3℃, and the water temperature was a bit higher. The members of the Polar Bear Club at Coney Island, New York are usually about the age of 60. Members must satisfy two requirements. First, they must get along well with everyone else in the group, this is very important because there are so many different kinds of people in the club. Polar Bears must also agree to swim outdoors at least twice a month from November through February.

Doctors do not agree about the medical effects of cold-water swimming. Some are worried about the dangers of a condition in which the body's temperature drops so low that finally the heart stops. Other doctors, however, point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.

The Polar Bears themselves are satisfied with the benefits (or advantages)of cold-water swimming. They say that their favorite form of exercise is very good for the circulatory system(循环系统)because it forces the blood to move fast to keep the body warm. Cold-water swimmers usually turn bright red after a few minutes in the water. A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.　

The main benefits(or advantages)of cold-water swimming are probably mental. The Polar Bears love to swim year-round;they find it fun and relaxing. As one 70-year-old woman says. "When I go into the water, I pour my troubles into the ocean and let them float away."

69. What is particular in American schools is that　　　　 .

A. there is some middle ground between the two teaching buildings

B. there are a lot of after-school activities

C. students usually take fourteen subjects in all

D. students go outside to enjoy themselves in a car