问题 单项选择题

在系统中加入了( )环节以后,不仅能使系统得到下垂的机械特性,而且也能加快过渡过程,改善系统的动态特性。

A.电压负反馈

B.电流负反馈

C.电压截止负反馈

D.电流截止负反馈

答案

参考答案:D

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    The last patient left his office. Mr. South had a look at the   1   on the wall. It was a quarter to six. It
means that he had to stay there for fifteen minutes. A friend of his asked him to dinner that evening. Of
course he should   2   some flowers for her. He brought out the purse and   3   the money in it. He had
sixty dollars and it was enough to do that. And then he   4   he bought a newspaper on his way to the
hospital after lunch. He was too busy to read it. Now he brought it out, but then came in a man   5   forty.
He looked at him carefully. The man looked   6  . Mr. South didn't know what he came for. 
    "What's wrong with you?" asked Mr. South. 
    "  7  , Mr. South," said the man, "But…"
    The man began to smile and said, "Don't you   8   me, Mr. South? You cured (治愈) my rheumatism
(风湿病) three years ago."
     "Mr. Bell?"
     "Yes. Did you   9   me not to get myself wet?"
     "Yes, I did," answered the  10 .
     "Well. I come here to ask you if you think it's OK for me to take a bath now?"
( )1. A. watch     
(     )2. A. buy       
(     )3. A. drew      
(     )4. A. forgot    
(     )5. A. at        
(     )6. A. healthy   
(     )7. A. Everything
(     )8. A. hear      
(     )9. A. say       
(     )10. A. doctor   
B. picture    
B. look for   
B. counted      
B. remembered   
B. for         
B. strange     
B. Nothing     
B. listen to 
B. tell        
B. nurse     
C. clock       
C. pick        
C. saw         
C. thought     
C. on          
C. weak       
C. Something    
C. remember  
C. hope       
C. patient  
D. map         
D. borrow      
D. found       
D. decided                           
D. about       
D. tall          
D. Anything     
D. help        
D. left         
D. friend    
选择题