问题 问答题 简答题

如何选择压力表的量程?

答案

参考答案:

为了防止仪表损坏,压力表所测压力的最大值一般不超过仪表测量上限的2/3:为了保证测量的准确度,被测压力不得低于标尺上限的1/3。当被测压力波动较大时,应使压力变化范围处在标尺上限的1/3~1/2处。

阅读理解

阅读理解。

      Television in the United States is free. To pay for programs, there are many advertisements. Often

these advertisements are short plays with actors. The following television advertisement is like many

others that Americans see daily.

     We see a man and his wife at the breakfast table. They have been married for a long time. They are

not speaking to each other. They haven't spoken to each other at the breakfast table for years. The

husband is reading his newspaper. We can't see his face. The wife looks very bored as she pours a cup

of coffee for him. Today, she is using a new kind of coffee for the first time. The husband picks up his

cup. He isn't very interested. He tastes his coffee. Suddenly he puts down his newspaper. Something is

different! Can it be the coffee? He takes another taste. It's wonderful! He smiles. He looks at his wife

and says in amazement,

     "Doris, when did you cut your hair?"

     Doris is pleased. She answers, "Two months ago."

     Doris asks, "Herbie, when did your hair begin to turn gray?"

     He replies, "A long time ago."

     Doris says, "Oh, very handsome."

     Now they aren't bored any more. Breakfast is different. Has a new kind of coffee changed their lives?

1. In the television advertisement, Doris looks bored because ______.      

A. she doesn't like the breakfast that morning

B. Her husband doesn't care much for her

C. she has been married to Herbie for a long time

D. Herbie isn't interested in the breakfast she cooks

2. The TV advertisement wants to tell the viewers ______.     

A. that advertisement can certainly increase goods production

B. to have a good laugh at the good couple

C. that a nice breakfast must go with nice coffee

D. to have an immediate try at the new coffee

3. This text is mainly about ______.      

A. who pays for TV programs in the United States

B. what a TV advertisement is usually like in the USA

C. why long married couples dislike speaking to each other

D. what made Herbie and Doris not bored any more

单项选择题