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问题 问答题 简答题

运行中的电动机应注意那些事项？

答案

参考答案：

（1）电动机运行电流不超过电动机的额定电流；电流发生过大摆动应停机检查。

（2）电动机各部位的声响及振动是否正常，如发现异常应及时处理。

（3）电动机的温升也不超过厂家的规定，如无规定时，A级绝缘不超过55℃，E级绝缘不超过60℃；B级绝缘不超过65℃。

（4）电动机滑动轴承温度不超过65℃；滚动轴承温度不超过75℃。

单项选择题

Are you a man or a mouse When people ask this question they want to know (1) you think you are a (2) person or a coward. But you will never really know the answer to this question (3) you are tested in real life. Some people (4) they are brave but when they come face to face with real (5) , they act like cowards. Others think of themselves as cowards, but when they meet danger, they act like (6)

Lenny had always thought of himself as a (7) person. He got worried before examinations. He worried about his job and health. All he wanted in life was to be safe and healthy. (8) , on January 15th, 2002, a plane crashed into the Potomac River in Washington. Lenny went to the river to see what was happening. He saw a woman in the (9) water. Lenny did not feel afraid. He kept very (10) and did a very dangerous thing. He jumped into the Potomac, (11) to the woman, and kept her head (12) the water. Seventy-eight people died that day. Thanks to Lenny, it was not (13) .

When you are in a very (14) situation and feel afraid, the body automatically produces a chemical in the blood. The chemical is called adrenalin. (15) adrenalin in the blood system, you actually feel per and per and are (16) to fight or run away. However, when you are absolutely terrified, the body can produce too much adrenalin. When this (17) , the muscles become very hard and you find you (18) move at all. You are then paralyzed with fear. This is (19) when we are very frightened, we sometimes say we’re "petrified". This word comes from the Greek word "petros", which means "stone". We are (20) frightened that we become stonelike.

18（）

A.needn’t 

B.can’t 

C.mustn’t 

D.shouldn’t
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单项选择题

分泌雄激素的细胞是（）。

A、精原细胞

B、支持细胞

C、初级精母细胞

D、睾丸间质细胞
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