Precipitation, commonly referred to as rainfall, is a measure of the quantity of water in the form of either rain, hall, or snow which reaches the ground, The average annual precipitation over the whole of the United States is thirty-six inches. It should be understood, however, that a foot of snow is not equal to a foot of precipitation. A general formula for computing the precipitation of snowfall is that thirty-- eight inches of snow is equal to one inch of precipitation. In New York State, for example, seventy-six inches of snow in one year would be recorded as only two inches of precipitation. The total annual precipitation Forty inches of rain would be recorded as forty inches of precipitation. The total annual precipitation would be recorded as forty-two inches. 查看更多

 

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It doesn't matter when or how much a person sleeps, but everyone needs some rest to stay alive. That's what all doctors thought, until they heard about Al Herpin.

  Al Herpin, it was said, never slept. He was 90 years old when doctors came to his home in New Jersey. They expected to find out that he needed sleep of some kind. But they were surprised. Though they watched him every hour of the day, they never saw Herpin sleeping. He did not even own a bed. He never needed one.

  The closest that Herpin came to resting was to sit in a rocking chair(摇椅) and read some news papers. The doctors were puzzled by this strange continuous sleeplessness. Herpin offered the only probable explanation of his condition. He remembered some talk about his mother having been injured several days before he was born.

The point of this story is that _______.

 A. We needn't feel surprised to find someone who doesn't sleep

 B. one person was found who actually didn't need any sleep

C. everyone needs some rest to stay alive

 D. not sleeping may help one to live longer

After watching him closely, the doctors believed that Al Herpin _______.

 A. needed some kind of sleep    B. slept while one was watching

 C. needed no sleep at all     D. nearly slept in a rocking chair

One suggested explanation of Herpin's sleeplessness was _______.

 A. his old age     

B. his not having a bed

 C. his magnificent physical condition

 D. his mother's injury while carrying him

The writer of the story obviously thinks that Al Herpin's sleeplessness ___.

 A. could be cured     B. could be explained

 C. was healthful      D. was uncommon  

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---Did you visit the famous museum ?

  ---No. We ______ it. But we spent too much time shopping.

  A. can't have visited       B. could have visited

  C. must have visited       D. shouldn't have visited

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The chances of discovering life on Neptune are about a million _____.

  A. at one    B. for one    C. to one    D. against one

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_____ his homework, he went out to play.

  A. Having done              B. Done

  C. He has done              D. He had done

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We have eight foreign teachers in our school,five of _______ are young ladies.

A. them   B. whom

C. who    D. which

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