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问题 单项选择题

机上失火时，三人灭火小组中灭火者的职责为（）。

A.B＋C+D

B.立即灭火

C.呼叫或发出信号

D.取用灭火瓶和防烟面罩

答案

参考答案：A

完形填空
阅读下面的短文并选择合适的答案完成这篇短文。
     Plants are very important living things. Life can not go on    1    plants. This is because plants can make
food    2    air, water and sunlight. Animals and man    3    do so. Animals get their    4    by eating plants
   5    animals, Man gets his food    6   eating plants and animals,    7   . So animals and man    8    plants to
live. This is    9   we find there are so many   10   around us.
( )1. A. with    
( )2. A. with    
( )3. A. mustn't
( )4. A. food    
( )5. A. too    
( )6. A. with    
( )7. A. too    
( )8. A. want    
( )9. A. why    
( )10. A. animals		B. without  
B. about    
B. needn't
B. water    
B. also    
B. of      
B. also    
B. wants    
B. how      
B. plants   		C. no    
C. from  
C. can't
C. drink  
C. and    
C. by    
C. or    
C. needs  
C. which  
C. air    		D. off          
D. of           
D. may not    
D. animals      
D. so          
D. from        
D. so          
D. need        
D. what        
D. livig things
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问答题 简答题

简述三相异步电机反接制动的工作原理。
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