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（附加题）如图所示，倾角为α=60°的斜面上，放一质量为1kg大小可以忽略的物体，用劲度系数k=100N/m的弹簧平行于斜面吊着，物体放在PQ之间任何位置都能处于静止状态，而超过这一范围，物体都会沿斜面滑动．若AP=22cm，AQ=8cm，试求物体与斜面间的最大静摩擦力的大小．（g=10m/s2）

答案

设弹簧的原长为l0．

在P点有：k（Lap-l0）=mgsin60°+Fmax （1）

在Q点有：k（Laq-l0）+Fmax=mgsin60°（2）

由（1）-（2）得：kLap-kLaq=2Fmax

代入数值的Fmax=7N

答：物体与斜面间的最大静摩擦力的大小是7N．

完形填空
完形填空。
     George Bernard Show once said, "America and Britain are two countries separated by the same language".
Many students of English worry (1)_______ about the differences between American and British English. In
fact, (2)_______, the differences are not (3)_______ large. Unlike, for example, Mandarin (普通话的) and
Cantonese speakers, speakers of the American and British (4)_______ of English can understand (5)_______
and communicate with very (6)_______ misunderstandings.
     When we talk about the American and British dialects of English we do not (7)________ pronunciation.
Both UK and US have several different regional (8)_______ within their own borders. Besides, there is no
(9)_______ to enforce a standard. If you (10)_______ the radio in New York, you will hear presenters speaking
(11)_______ New York accents. If you were then to tune into a (12)_______ radio station you would hear
presenters speaking with Californian accents. Likewise, anyone who has ever watched BBC will know that their
(13)_______ have a wide range of accents, from (14)_______ to Indian. Native English speakers are able to
understand most regional accents (15)_______ a large degree.
     The main difference between American and British English has something to do (16)_______ writing. It is
in grammar, spelling and word usage (17)_______ the two dialects differ the most. (18)_______, when writing
English, you should decide which one to use and try to use it as consistently as possible.
     The greatest difference between American and British English (19)_______ the choice of vocabulary. The
same word can have (20)_______ meanings. When Americans say that someone is mean they are expressing
that that person is bad-humored. Whereas, in Britain, a mean person is someone who is not generous. There are
many more examples and most dictionaries will explain them.
( )1. A. much too           
( )2. A. relative speaking
( )3. A. that               
( )4. A. languages          
( )5. A. each               
( )6. A. little           
( )7. A. refer to           
( )8. A. accents            
( )9. A. try                
( )10. A. listen to          
( )11. A. on                 
( )12. A. Californian        
( )13. A. teachers           
( )14. A. Scottish           
( )15. A. in                 
( )16. A. with               
( )17. A. where              
( )18. A. However            
( )19. A. there is           
( )20. A. same              		B. too much           
B. speaking relatively    
B. it                 
B. dialects           
B. other              
B. a little           
B. point to           
B. languages          
B. attempt            
B. hear               
B. in                 
B. American           
B. leaders            
B. French             
B. on                 
B. upon               
B. which              
B. But                
B. has                
B. different           		C. too very              
C. relatively speaking    
C. what                  
C. speeches              
C. each other            
C. a few                 
C. throw to              
C. ways                  
C. manage                
C. feel                  
C. with                  
C. British               
C. presenters            
C. Japanese              
C. to                    
C. over                  
C. that                  
C. Therefore             
C. lies in             
C. all                  		D. very too         
D. speaking relative     
D. which            
D. speaking         
D. other each       
D. few              
D. look to          
D. speeches         
D. advise           
D. watch            
D. at               
D. Chinese          
D. directors        
D. Chinese          
D. at               
D. above            
D. what             
D. So               
D. have             
D. one              
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单项选择题

在左边四个图形中，哪个可以拼接成右图（）

A.A

B.B

C.C

D.D
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