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问题 计算题

2008年初，我国南方地区出现了罕见的冰雪灾害，其中融雪剂在抗灾中起到了很大的作用。有一种效果好、无污染的融雪剂，其主要成分是醋酸钾【化学式是CH3COOK】。请根据化学式通过计算回答：

（1）醋酸钾分子的相对分子质量是多少？

（2）说它无污染主要是由于其组成中有__________元素，融雪后形成溶液恰好又是路边植物很好的肥料。请计算化学式中此种元素的质量分数是多少？

答案

（1）98

（2）k；39.8%

选择题

-I'm dead tired.I can't walk any farther,Jenny.

-________,Tommy.You can do it.[ ]

A．No problem      

B．No hurry

C．Come on  

D．That's OK
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       The bicycle is one of the simplest (最简单的) yet most useful inventions in the world. What is most
surprising is that it was not invented earlier,   1   the great inventor Leonardo da Vinci had drawn pictures
for bicycles and also for flying machines and some other things. Those things  were not produced   2   long after he died.
       A person riding a bicycle use   3   energy(能量)to make the bicycle move, and there is no pollution
at all when you are riding. Even so, m developed   4  , most people don't travel to  work by bicycle. It is
not because the bicycles are expensive or people feel   5   if they ride to work. It's because    6   cars on
the roads becomes larger. It certainly becomes   7   to ride a bi-cycle. As a result, more people put their
bicycles away and go to work   8   their cars and, in this way, the situation(情形)is made more serious.  9   the best way to make riding safer and more popular is to create paths(开设通道)only for bicycles, and
to make   10    so difficult and expensive for drivers to take their cars into the city that they will go back
to use their bicycles.


( )1. A．although          
( )2. A．when              
( )3. A．much              
( )4. A．world            
( )5. A．comfortable      
( )6. A．the number of    
( )7. A．safer            
( )8. A．by                
( )9. A. Always            
( )10.A．it                
                                          		B．so              
B．before          
B．quite a lot of  
B．countries        
B．1ucky            
B．a number of      
B．more dangerous  
B．in              
B．May be          
B．them          
C．but              
C．since            
C．very little      
C．1and            
C．sorry            
C．this kind of    
C．much dangerous  
C．use              
C．Perhaps          
C．us               
                                		D．because         
D．until           
D．many            
D．earth           
D．tired           
D．a kind of       
D．safe            
D．drive           
D．Nearly          
D．that      
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