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问题 不定项选择

如图所示，绝缘轻杆两端固定带电小球A和B，轻杆处于水平向右的匀强电场中，不考虑两球之间的相互作用。初始时轻杆与电场线垂直（如图中实线位置），将杆向右平移的同时顺时针转过90°（如图中虚线位置），发现A、B两球电势能之和不变。根据图中给出的位置关系，可判断下列说法中正确的是

[ ]

A．A球一定带正电荷，B球一定带负电荷

B．A、B两球带电量的绝对值之比qA∶qB=1∶2

C．A球电势能一定增加

D．电场力对A球和B球都不做功

答案

答案：B

完形填空
完形填空。

     Sam had a dog. Its name was Tod. It was very helpful, but it ate too much. So he didn't like it, he wanted
to    1   it. He    2   Tod and put it in a small boat. He rowed the boat to the   3    of a big river. Just as he   4   
the poor animal into the river, the boat began to go down.    5   the man and Tod    6   into the river.
     Tod was able to swim,    7   Sam couldn't. The dog bit the rope (绳子) and broke (破坏) it. It tried its best
to swim to   8    Sam. The man was saved, so he was very thankful for the dog and he didn't want to kill the
dog    9  . From then on, he gave the dog as    10   as it wanted.

( )1. A. sell     
(     )2. A. tied     
(     )3. A. front    
(     )4. A. threw    
(     )5. A. Neither  
(     )6. A. fell     
(     )7. A. because  
(     )8. A. kill     
(     )9. A. no more  
(     )10. A. little    		B. buy       
B. pulled    
B. foot      
B. carried   
B. Nor       
B. swam           
B. though    
B. save      
B. any more  
B. few       		C. beat       
C. pushed     
C. side       
C. sent      
C. Each        
C. lost              
C. but         
C. meet        
C. no longer  
C. many      		D. kill
D. closed                      
D. middle                     
D. brought                    
D. Both                        
D. jumped                       
D. when                         
D. hit                          
D. not more                      
D. much                    
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填空题

运行下列XY.PRG程序后，将在屏幕上显示如下的乘法表： 1 2 4 3 6 9 4 8 12 16 5 10 15 20 25 6 12 18 24 30 36 7 14 21 28 35 42 49 8 16 24 32 40 48 56 64 9 18 27 36 45 54 63 72 81 请对下面的程序填空： ***计算乘法XY．PRG*** SET TALK OFF CLEAR FOR J=1 TO 9 FOR [12] [13] EMDFOR ENDFOR RETURN
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