问题 问答题

金属加工常用的激光器是哪些?它们之间的区别除了在工件物质以外,还在于什么?

答案

参考答案:

金属加工常用的激光器有两种,一种是固体激光器,如红宝石激光器、玻璃激光器、YAG激光器和金绿宝石激光器;另外一种是气体激光器:如CO2激光器、氩激光器等。它们之间的区别除了在工作介质外,还在于激光波长、输出功率、应用范围等。

阅读理解

阅读短文,选择正确答案。

     A man was looking for things of the old times. One day he came to a village and found a blue bowl. It looked

very old. The bowl was on the ground and a cat was drinking milk from it. A farmer, the owner of the cat, was

sitting beside the bowl. The man did not want the farmer to know that he was interested in the bowl. So he said

to him in a soft voice, "What a nice cat you have! Will you sell it to me?"

    "How much will you give me for the cat?" the farmer asked.

    "Thirty dollars. Would that be enough?" Later, the farmer agreed. After he paid the farmer, the man said,

"This cat is used to eating with his bowl. May I take this bowl with the cat?" But the farmer said,"I'm sorry I

can't give you the bowl. Thanks to the bowl, I have sold thirty cats."

1. What does the sentence "A man was looking for things of the old times" mean? [ ]

A. He lost things in the past and wanted to get them back.

B. He liked talking to old people.

C. He liked keeping old things.

2. Why did the man want to buy the cat? [ ]

A. He liked it better than the bowl.

B. It was sold with the bowl.

C. He thought he could easily get the bowl after he bought the cat.

3. After he bought the cat, the man asked for the bowl, because he thought            .[ ]

A. the cat couldn't live without the bowl

B. the farmer didn't know the value of the bowl

C. the bowl should go with the cat

4. The farmer kept the bowl so that he could             . [ ]

A. let another cat use it

B. sell more cats

C. sell more bowls

5. From the story we can see that the farmer            . [ ]

A. had only one bowl

B. didn't like cats

C. was cleverer

单项选择题 B1型题