问题 问答题 简答题

焊接区的水份对气孔的生成有何影响?

答案

参考答案:

由于水是由氢和氧两种元素组成的,在常温时,水是比较稳定的,但在高温时可分解为氢气和氧气,因而既增加了氢气孔的生成倾向,也增加了一氧化碳气孔的生成倾向,因而焊接区水份的存在对焊接是极为不利的。

阅读理解

阅读理解。

      A lot of boys and girls in western countries are wearing the same clothes, and many boys have long

hair, so it is difficult to tell whether they are boys or not.

      One day an old man went for a walk in a park in Washington and when he was tired, he sat down

on a chair by a swimming pool. A young person was standing on the other side of the pool.

     "Oh!" the old man said to the person sitting next to him, "Do you see the person with the loose

clothes and long hair? Is it a boy or a girl?"

      "A girl," said the person, "She is my daughter. "

      "Oh!" the old man said quickly, "Please forgive me. I don't know that you are her mother. "

      "I'm not," said the person, "I'm her father. "

1. What did the old man see on the other side of the pool?

A. A girl. 

B. A boy. 

C. An old woman. 

D. A man. 

2. The old man thought the person sitting next to him was ____. 

A. a woman

B. a man

C. a girl

D. a boy

3. "Please forgive me." in the passage means "____" .

A. I'm not sure. 

B. I'm surprised.  

C. I'm sorry. 

D. I'm not living here. 

4. Which is right according to the passage?

A. Most people in western countries wear the same clothes. 

B. The old man thought the person next to him was a man. 

C. It's difficult to tell boys from girls because they wear the same clothes. 

D. Sometimes men also have long hairs as women in western countries. 

5. Which can be the best title for the passage?

A. Are they wearing the same clothes?

B. Can you tell boys from girls?

C. Are they boys or girls?

D. What's wrong with the boys?

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