15. From the passage we can see that the writer’s attitude toward “village life” is ___________ 
A. positive   B. negative  C. neutral   D. unclear 

Passage 4 

Questions 16 to 20 are based on the following passage. 

 We all know that it is possible for ordinary people to make their on the equator (赤道), although often they may feel uncomfortably hot there. Millions do it. but as for the North Pole(北极)—— we that it is not only a dangerously cold place, but that people like you and me would find it quite impossible to live there. At the present time only the scientists and explorers can do so, and they use special equipment. Men had been traveling across and around the equator on wheels, on their feet or in ships for thousands of years; but only a few men, with great difficulty and in very recent time, have ever crossed the ice to the North Pole. So it may surprise you to learn that, when traveling by air, it is really safer to fly over the North Pole than over the equator. Of course, this is not true about landings in the polar region (which passenger aeroplanes do not make), but the weather, if we are flying at a height of 5,000 meters above the Pole, is a delight. At 4 000 meters and more above the earth you can always be that you will not see a cloud in the sky as far as the eye can reach. In the tropics (热带), on the other hand, you are not certain to keep clear of bad weather even at such heights as 18,000 or 20,000 meters. 

Aeroplanes can’t climb as high or as quickly in cold air as in warm. Nor can clouds. In practice, this is an advantage to the aeroplane, which is already at a good height when it reaches the polar region and so does not need to climb, while at the same time cold air keeps the clouds down low.  

16. “Millions do it.” In this sentence “do it” refers to _________ 
A. feeling uncomfortably hot on the equator 
B. flying over the North Pole 
C. flying over the equator 
D. making homes on the equator 

17. The polar region is ________ 
A. a good place to land at by aeroplane 
B. a good place to fly over 
C. a good place to fly over 
D. a good place to live in 

18. It is a delight to fly at the Pole because there _________ 
A. planes fly higher than at the equator 
B. the eyes can reach about 4,000 meters 
C. planes are clear of bad weather 
D. planes fly more quickly than at the equator. 

19. Aeroplanes can climb quickly ________ 
A. in warm air 
B. in cold air 
C. when it reaches the polar region 
D. only when the clouds are down low 

20. Aeroplanes usually do not need to climb quickly or fly high in the polar region because _________