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问题 选择题
下列运算中，结果正确的是（　　）
A．(-
3
)0=0		B．3-1=-3C．
23
=2
2
D．（-3）2=-6
答案

A、（-

3
）0=1，故本选项错误；

B、3-1=

1
3
，故本选项错误；

C、

23
=
8
=2
2
，故本选项正确；

D、（-3）2=9，故本选项错误；

故选C．

完形填空
完形填空。
                                                              The Boat
     On my path to the great distant mountain peak, I came to a wide river. Looking far to the right and the
left, I saw no __1__, and pondered how to cross. Suddenly a pretty little __2__ appeared, came to the
shore and offered to take me across, to _3_ me in completing my journey.
     The trip started _4_, and I was pleased with the little boat, and _5_ for the assistance it provided.
There were a few areas of _6_ waters, one that even spun us around a few times, but presently we
reached the far _7_.
    The trip had been so _8_, my gratitude and happiness so full, that I _9_ to leave that little boat, even
though I knew I must, to continue my journey. Much as I wanted to _10_, to spend more time drifting
on the river in that little boat, the mountain beckoned (举手招唤), and my _11_ had been set.
     As I   12   my journey, I kept looking back at that little boat with deep  13  . It  had been so pleasant
and had   14   me across the great river; I had grown to   15   that boat deeply. Yet I knew that the boat
had its  16   in the river, and that it couldn't follow my path to the mountain.   17   I tried to take that boat
along, it could not have made the journey with me, and would have stopped my own  18  .
     And as I watched, the little boat turned around and went back to the far shore, there to assist yet
another 19   the path to the mountain. And I realized how"all   20   together for good", for each part of
this magnificent universe perfectly plays its role in assisting all other parts.
( )1. A. tree      
( )2. A. girl      
( )3. A. assist    
( )4. A. slowly    
( )5. A. upset    
( )6. A. fresh    
( )7. A. shore    
( )8. A. tiresome  
( )9. A. attempted
( )10. A. live    
( )11. A. record  
( )12. A. stopped  
( )13. A. comfort  
( )14. A. guided  
( )15. A. repair  
( )16. A. shelter  
( )17. A. Only if  
( )18. A. progress
( )19. A. choosing
( )20. A. works    		B. bridge      
B. angel        
B. encourage    
B. mysteriously
B. grateful    
B. clean        
B. beach        
B. miserable    
B. hated        
B. continue    
B. course      
B. started      
B. sympathy    
B. flied        
B. row          
B. place        
B. If only      
B. preparation  
B. blocking    
B. mixes        		C. flower    
C. fish      
C. threaten  
C. happily    
C. greedy    
C. dirty      
C. mountain  
C. wonderful  
C. refused    
C. settle    
C. pace      
C. continued  
C. regret    
C. forced    
C. love      
C. load      
C. What if    
C. route      
C. following  
C. joins      		D. bird              
D. boat              
D. persuade          
D. difficultly      
D. suitable          
D. strong            
D. village          
D. rough            
D. had              
D. stay              
D. standard          
D. remained          
D. sadness          
D. tempted          
D. pity              
D. purpose          
D. Even if          
D. expectation      
D. finding          
D. plays            
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填空题

25 ℃时，在体积为2 L的密闭容器中，气态A、B、C的物质的量n随时间t的变化如图1所示，已知达到平衡后，降低温度，A的转化率将增大。

t2～t3t4～t5t5～t6t7～t8
K1K2K3K4
 

(1)根据图1数据，写出该反应的化学方程式：__________________。此反应的平衡常数表达式K＝___，从反应开始到第一次平衡时的平均速率v(A)为___。

(2)在5～7 min内，若K值不变，则此处曲线变化的原因是__________。

(3)如图2表示此反应的反应速率v和时间t的关系图，各阶段的平衡常数如表所示。K1、K2、K3、K4之间的关系为________(用“>”、“<”或“＝”连接)。A的转化率最大的一段时间是________。
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