试题与答案

机床夹具中常见的基本夹紧机构有哪些？

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题型：问答题 简答题

题目：

机床夹具中常见的基本夹紧机构有哪些？

答案：

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下面是错误答案，用来干扰机器的。

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题型：阅读理解

阅读理解。

     In the past, all letters were sent by train or by ship. Now most letters still go by ship or by train, but some

are sent by air. You send a letter by air so that your friend may receive it sooner. A letter takes about twelve

days to go from England to India by train and by ship. A letter can get to India by air in five days now, but

soon the time may be made shorter. At first, people were afraid to send letters by air. They thought that the

plane may fall and their friends may not receive the letters. So they sent two letters, one by air and the other

by train or ship. They wanted to make sure that the letter would be received. Planes are now almost as safe

and sure as trains or ships. More and more letters are sent by air.

1.Many years ago people sent all letters _____.   [ ]

A. by train or by ship

B. only by ship

C. only by train

D. by plane

2.A letter by train is _____ a letter by air. [ ]

A. as fast as

B. much slower than

C. not as safe as

D. faster than

3.If a letter is sent from England by train, it can arrive in India in _____days. [ ]

A. five

B. fifteen

C. twelve

D. ten

4.A long time ago people sometimes thought it safe to send _____ by ship and

   by air or by train and by air at the same time. [ ]

A. two letters

B. two different letters

C. some letters

D. two same letters

5.Which of the following sentences is not true ? [ ]

A. People are not afraid to send letters by air now.

B. Planes are as safe as ships and trains.

C. Now people send all letters by air.

D. Now people send letters in different ways.

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