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问题 选择题

列车长为L，铁路桥长也是L，列车沿平直轨道匀加速过桥，车头过桥头的速度是v1，车头过桥尾的速度是v2，则车尾通过桥尾时的速度为（　　）

A．

v1+v2
2

B．2v2-v1

C．

v21
+
v22
2

D．

2
v22-
v21

答案

火车车头从桥头到桥尾运动的过程中有：

     2aL=v22-v12  ①

   火车车头从桥头到车尾通过桥尾的过程中有：

     2a•2L=v 2-v12  ②

由①②得：

v=

2
v22
-
v21

故选D．

完形填空
阅读下面的材料,掌握其大意,然后从短文后各题所给的A、B、C、D四个选项中,选择最佳选项。    

     Shanghai is a modern city. It likes new things. Shanghai was a(n)   1   city even a hundred years ago,
so there is a(n)   2   -if Shanghai likes new things, what should it do with the old things?    
     The government (政府) thinks a modern city should have both old and new things. The Waibaidu
Bridge is an example. People built it over one hundred years ago. When it   3   , the government decided
to spend a lot of money rebuilding (重建) it. The government did this   4   it believes that the city needs to
remember its history.    
     There are also some people working to save historical (历史的) things. Mr Wang is one of   5   .
When he was fifty years old, he   6   from Canada to Shanghai, his hometown, and started to collect
materials (材料) of old houses. He believed that old houses were a(n)   7   part of China's history so he
tried his best to save them. He   8   the materials to other places and rebuilt them.    
     You can also help to remember the past. Get a camera and take   9   of old things. Ask old people to
tell you stories about Shanghai's  10   . It can be fun and you can see how some new things in the past are
old now.

( )1. A.small
( )2. A.mistake
( )3. A.fell down
( )4. A.if    
( )5. A.us    
( )6. A.walked  
( )7. A.light
( )8. A.reported  
( )9. A.dreams  
( )10. A.past  		B.big       
B.question     
B.made up     
B.though   
B.him      
B.returned             
B.underground    
B.provided   
B.photos      
B.attitude 		C.peaceful
C.plan  
C.caught up
C.so     
C.them                     
C.swam  
C.difficult
C.took  
C.notes
C.tomorrow		D.tiring              
D.answer              
D.gave up             
D.because             
D.you                 
D.wrote               
D.important           
D.considered          
D.conclusions         
D.present          
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问答题 论述题

结合学术研究的新成果试析抗日战争胜利的代价。
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