问题 问答题 简答题

往复式压缩机的工作原理是怎样的?

答案

参考答案:

当曲轴由电动机带动作回转运动时,曲轴连杆机构把转动变为移动,使活塞在气缸中作往复直线运动,当活塞向左运行时,活塞左边的气体受到压缩,从排气阀送出去,直到活塞移动到左端时止(压缩、排气过程)。同时活塞右边的空间体积增大,压力下降,气体顶开右边的吸气阀进入气缸,直到活塞移动到左端时止(吸气过程),当活塞从左向右移动时,活塞右边压缩排气,左边吸气。

阅读理解

阅读理解。

     A young man once went to buy a pair of pants. When he got home, he went upstairs (上楼) to his

bedroom and put them on. He found that they were two inches (英寸) long.

     Then he came out of his room to see his mother and his two sisters. They were washing something in

the kitchen. "These new pants are too long, they need to be shortened (缩短) about two inches. Would

one  of you  like to do this for me, please?" His  mother  and  sisters  were  busy and none of them said

anything. The mother went upstairs after she had finished washing and shortened the pants two inches.

But she didn't tell her daughters about it.

     Later on, after supper, the elder sister remembered her brother's pants. So she went upstairs without

saying to anyone, and shortened the pants two inches.

    The younger sister went to the cinema, but when she came back, she also remembered what her

brother had said. So she ran upstairs, and took two inches off the legs of the new pants.

1. The new pants were _______.      

A. too long for the young man      

B. two inches long

C. six inches long                

D. too short for the young man    

2. The young man asked ______to shorten his pants.

A. his mother and his two sisters      

B. his mother and one of his sister

C. his mother                

D. his mother or one of his two sisters

3. ______, his elder sister shorten his pants.

A. After supper            

B. After the mother finished washing

C. After the young man went upstairs

D. After the younger sister went to the cinema

4. How many inches were the legs of the new pants shortened by at last?

A. Two.  

B. Four.  

C. Six.  

D. Eight.

5. When the young man put on the pants, he would _______.

A. feel happy  

B. be very sad  

C. thank his family  

D. be very excited

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