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问题 单项选择题

无限大真空中，点电荷qA与qB分别位于等边三角形ABC的两个顶点上(题1-52图)，若qA在C点单独作用产生的场强大小为E，而qB=-qA，则qA与qB共同作用在C点产生的场强大小为（）。

A．E

B．2E

C．E

D．0

答案

参考答案：A

单项选择题

蛛网膜下腔阻滞麻醉时，最常用的穿刺部位是（）

A.腰3-4

B.胸12～腰1

C.腰4-5

D.胸10-11

E.骶3
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完形填空
完形填空。
     There are many different ways of seeing a town for the first time. One of them is to walk around it, guide-
book   1   hand. Of course, we may   2   with our guide-books the history and   3   developments of a town
and get to know them.   4   then, if we take out time and   5   in a town for a while, we may get to know it
better. When we   6   it as a whole, we begin to have some   7  , which even the best guide-books do not
answer. Why is the town just   8   this, this shape, this plan, this size? Why do its streets   9   in this particular
way, and not in any  10  why?
     Here even the best guide-book  11  us. One can't find in it the information about how a town has developed
to the  12  appearance. It may not describe the original (最初的)  13  of a town. However, one may get some
idea of what I  14  look like by walking around the town. One can also imagine  15  the town was first planned
and . Then one can learn more about in what direction the town  16  to develop.
     What is the  17  of studying towns in the way? For me, it is  18  that one gets a greater depth of pleasure
by visiting and seeing a town with one's own eyes. A  19  visit to a town may help one better understand why
it is attractive  20  just reading about it in a guide-book.
( )1. A. in      
( )2. A. write   
( )3. A. strange 
( )4. A. But     
( )5. A. look at 
( )6. A. look at 
( )7. A. ideas   
( )8. A. of      
( )9. A. open    
( )10. A. one     
( )11. A. helps   
( )12. A. old     
( )13. A. capital 
( )14. A. used to       
( )15. A. what    
( )16. A. stops   
( )17. A. point   
( )18. A. nearly  
( )19. A. costly  
( )20. A. from    

B. at               
B. study         
B. similar     
B. Before            
B. work          
B. look after   
B. opinions      
B. for         
B. run              
B. more           
B. tricks         
B. normal               
B. meaning        
B. seemed to     
B. how            
B. appears        
B. view            
B. simply       
B. formal       
B. than        

C. by              
C. tell           
C. separate  
C. Since            
C. stay            
C. look for    
C. feelings     
C. like        
C. begin         
C. other         
C. fails     
C. first             
C. design        
C. had to       
C. when             
C. starts        
C. problem       
C. generally          
C. group        
C. through          		D. on                   
D. remember             
D. special       
D. Until                
D. wait                     
D. look up         
D. questions         
D. as              
D. move                 
D. such                 
D. satisfies               
D. present               
D. change               
D. happened to     
 D. where                   
D. continues         
D. difficulty           
D. hardly                
D. personal            
D. with          
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