问题 选择题

设f0(x)=sinx,f1(x)=f0(x),f2(x)=f1(x),…,fn+1(x)=fn(x),n∈N,则f2010(x)=(  )

A.cosx

B.-cosx

C.sinx

D.-sinx

答案

由题意f0(x)=sinx,f1(x)=f0(x)=cosx,f2(x)=f1(x)=-sinx,f3(x)=f2(x)=-cosx,f4(x)=f3(x)=sinx,由此可知,在逐次求导的过程中,所得的函数呈周期性变化,从0开始计,周期是4,∵2011=4×502+3,f2010(x)是一周中的第三个函数,故f2010(x)=-sinx

故选D

选择题
完形填空
完形填空
     Carolyn Stradley is the founder of C&S Paving Inc(铺路公司)in Atlanta, USA. In the following
account. She recalls the job that challenged her   1   and skill but left her flying high.
    ¨When the Atlanta Airport was under  2  . in 1979, we were a new company struggling to make it
National Car Rental wanted to have 2,500 square meters of dirt paved    3   the cars could be on site 
  4    the airport opened. and the official opening was only ten days away !      5   other local paving
company wanted to do the job,    6   it couldn't be done. in such a short time. "
      " Because we were new and really needed the work ,we were    7   to try harder. We gave National
Car Rental our offer and   8   our best effort to get the job finished within ten days. We also   9   them that
if we failed,they would be no worse off,   10   they had plenty to gain if we succeeded. "
     "We got the job and immediately went into   11  . Working at night needed lights, so I rented a machine
to produce electricity for the site. Our   12  challenge was to keep the rock mixture   13  enough. All the
available water wagons (洒水车) were rented  out  for  the  airport construction,and we certainly couldn't
afford to buy a new one.   14   ,I got a special     15    To rent fire engine hoses (消防水龙带)  and
connect them to nearby hydrants  (消
防栓);then I   16  held one of those hoses to   17   down the rock. '
     "Those ten days were filled with challenges that  18   one creative idea after another. Nine days later,
the night before the airport opened , National Car Rental was the  19    company that had cars on the
parking lot. "
     "The key to our success was having the   20  to take on any job and then being creative in our
approach to getting it done. "
( )1. A. kindness      
( )2. A. construction  
( )3. A. after        
( )4. A. while        
( )5. A. Some          
( )6. A. stating      
( )7. A. able          
( )8. A. supported    
( )9. A. asked        
( )10. A. though      
( )11. A. discussion  
( )12. A. next        
( )13. A. cold        
( )14. A. Naturally    
( )15. A . excuse      
( )16. A. exactly      
( )17. A. pull        
( )18. A. required    
( )19. A. hest        
( )20. A. courage      
B. patience  
B. repair    
B. as        
B. since      
B. Any        
B. reporting  
B. nervous    
B. promised  
B. surprised  
B. but        
B. action    
B. first      
B. wet        
B. Obviously  
B. order      
B. personally
B. knock      
B. mixed      
B. last      
B. interest  
C. imagination    
C. control        
C. for            
C. where          
C. No              
C. relling        
C. afraid          
C. continued      
C. reminded        
C. as              
C. practice        
C. past            
C. loose          
C. Meanwhile      
C. permit          
C. angrily        
C. hit            
C. followed        
C. second          
C. hope            
D. experience  
D. development  
D. so          
D. when        
D. Every        
D. warning      
D. willing      
D. improved    
D. demanded    
D. unless      
D. production  
D. previous    
D. clean        
D. Instead      
D. reason      
D. hardly      
D. water        
D. formed      
D. only        
D. chance