2.Don't go beyond your abilities.Most swimmers know enough not to swim too far from the bank or the beach,Showing off by doing dangerous tricks is no good.

Swim safely and you will continue to swim and alive.

1.Never swim alone!No matter how good you are in the water,don't risk drowning by swimming alone.If you swim by yourself,with no life guards or friends with you,you may get into trouble.

68.The passage is mainly about_____.

A.the requirements of the Polar Bear Club

B.a group of cold-water-swimming livers

C.the Polar Bears' life in New York

D.doctors' ideas about cold-water swimming

D

Swimming is one of those activities that can be learned early in life.Little children can learn to swim as soon as they walk.In fact,you need the same skills in walking as in swimming. However,I believe that five is the best age to learn.By five or six,a child knows fear of water,a very important thing to know.It's wise to be afraid,to recognize true danger.Young ones understand that the water can sometimes be very dangerous.

To really benefit from swimming,every swimmer should learn,as soon as possible,these four basic strokes;butterfly,backstroke,breastroke,and crawl.I feel that one of these-the breaststroke-is different from the others,since some young swimmers use this stroke naturally,without any training.

In swimming there are certain rules every swimmer should follow:

67.The Polar Bears like to swim year-round,for_____.

A.it is an easy way ot keep the body warm in winter

B.they can remain young

C.they find it enjoyable and interesting

D.they might meet fewer troubles in life

66.According to the passage,some doctors believe it is true that_____.

A.Polar Bears are bears swimming in freezing water

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

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

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

65.The members of the Polar Bear Club must meet the following requirements except that_____.

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

B.they must reach the age of 60

C.they should be easy to make friends with

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

64.Extract 2 is probably taken from_____.

A.a computer textbook B.a company's advertisement

C.a teach-yourself computer book D. a children's guide to computers

C

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 little 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.

Dcotors don't agree about the medical effects of cold-winter 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 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 of cold-water swimming are probably mental.The Polar Bears love to swim all year round;they find it fun and relaxing.As one 70-year-old woman says,"When I go into water,I pour my troubles into the ocean and let them float away."

63.If you think of the circle of large standing stones as a computer,_____.

A.the shadow is the input and the position is the output B.the sunlight is the input and the calendar is the output

C.the position is the input and the sunlight is the output D.the calendar is the input and the shadow is the output

62.Why does the writer talk about Stonechenge in Extract 1?

A.To give an example of the very first computer. B.To show that computers are older than mankind.

C.To tell the difference between the past and the present. D.To give another very of explaining computers.

61.The writer introduces the words such as "input" and "output" in order to_____.

A.introduce people to computer language B.show computer language is the same as English

　C.help people some scientific language D.give people some scientific language