4. What does the underlined word "attribute"in Para.1 mean?

　　A. It means "contribute". B. It means "cause".

　　C. It means "owe". D. It means "devote".

　　B

　　The Arctic is a polar region. It surrounds the North Pole.

　　Like Antarctica, the Arctic is a land of ice and snow. Antarctica holds the record for a low temperature reading - 125 degrees Fahrenheit below zero. Reading of 85 degrees below zero is common in Antarctica. Winter temperatures average 30 degrees below zero in the Arctic. At the South Pole the winter average is about 73 degrees below zero.

　　One thing alone makes it almost impossible for men to live in Antarctica and in parts of the Arctic. This one thing is the low temperature - the killing chill of far North and the polar South.

　　To survive, men must wear the warmest possible clothing. They must build windproof shelters. They must keep heaters going at all times. Not even for a moment can they be unprotected against the below­zero temperatures.

　　Men have a way of providing for themselves. Polar explorers wrap themselves in warm coats and furs. The cold makes life difficult. But the explorers can stay alive.

　　What about animals？Can they survive？Do we find plants？Do we find life in the Arctic and in Antarctica? Yes, we do. There is life in the oceans. There is life on land.

　　Antarctica, as we have seen, is a cold place indeed. But this has not always been the case. Expedition (探险) scientists have discovered that Antarctica has not always been a frozen continent. At one time the weather in Antarctica may have been much like our own.

　　Explorers have discovered coal in Antarctica. This leads them to believe that Antarctica at one time was a land of swamps and forests. Heat and moisture must have kept the trees in the forests alive.

　　5. The lowest temperature that man has ever known was recorded ________.

　　A. in Antarctica　　 　B. in the Arctic

　　C. at the North Pole D. in the polar region

　　6. Polar explorers can stay alive there because they ________.

　　A. stay inside the building there

　　B. have their own way to keep warm

　　C. are stronger than other people

　　D. have no heaters and windproof shelters

　　7. Which of the following is NOT true according to the passage?

A. Man can survive in polar areas as long as they can keep warm.