房间空气调节器压缩机过热继电器动作的原因（）。

阅读短文，根据短文内容选择正确答案。       

     Food is important (重要) for everyone,but not everyone has time to think about which food is 

good. Many Americans think that fast food is very convenient (方便的). They like to have lunch 

at places like McDonald's. They eat fast food about twice a week. They want to buy the most 

delicious fast food, not the healthiest (最健康) food.          

     Now each American eats about three hamburgers and four bags of potato chips     every week.

 That is why more and more people are becoming fat. Most Americans know that fast food isn't 

good for them, but it seems that they can't stop eating it. In fact,more and more people are eating 

fast food. 96% of American primary school students know about McDonald's. In America, 33% 

of the children are too heavy. This makes it hard (困难) for them to move around and go up and 

down stairs (楼梯). They will have health problems (健康问题) later in life. Of course it's not only 

young people who are getting heavier. It's all Americans.

1. What is "potato chip?"

A. a kind of healthy food.

B. A kind of snack.

C. A kind of sea food.

2. How many children are too heavy in America?           

A. 67%of them.      

B. 96%of them.      

C. 33%of them.

3. Why are many Americans too heavy?            

A. Because they eat much food.

B. Because they eat too much fast food.

C. Because they eat too much healthy food.

4. Which is TRUE according to the passage (根据短文)?           

A. Americans don't like eating lunch at McDonald's.

B. It's not good for us to eat too much fast food.

C. 4% of American primary school students know about McDonald's.

5. What is the best title (题目) for the passage?          

A. Fast Food

B. American Health Problems

C. American Children like Fast Food

闸瓦的作用是什么？闸瓦的最大磨耗量是多少？

中期计划的年限是( )

A．4个月
B．7个月
C．2年
D．3～5年
E．8个月

安全工器具在每次使用前，必须进行哪些常规检查?

水位观测方法可根据实际情况进行选择。一般采用（）或（）测量，有条件时可采用自计水位仪，但需妥善装置，并定时检查。