问题 单项选择题

关于电容器,下列说法哪一种不正确()

A.平板电容器的容量与极板的重叠面积和电介常数成正比,与极板间的距离成反比

B.电容器是消耗电场能量的元件

C.平板电容器的容量,极板间充满均匀电介质时比极板间真空时增加了r倍

D.若额定耐压值选择过小,电容器将被击穿

答案

参考答案:B

完形填空
完形填空。
     "I don't have to go to school. My school __1__ me!" Sara showed me her room. "This is my
classroom and this is my teacher and the other __2_ " She pointed to a large radio with a microphone.
Sara lives with her parents on a farm in Central Australia. It's about 60 miles from her farm
to her neighbors.
     She can't go to __3__ because her farm is so far away from __4__. There are a lot of children like
her in Australia. They use the "School of the Air". There are 12 of __5__ for children in the outback
(内地) of Australia. They are at these schools until they are about 12 years old. Sara said, "We talk to
our teachers every day on the __6__. And our __7__ last about 30 minutes. Our teachers __8__ us the
class work and we do it before our lessons. Twice a year our teacher__9__ us, and once a year all the
students _10__. That's the best time of the year. "
( )1. A. comes  to          
( )2. A. neighbors          
( )3. A. hospitals          
( )4. A. the nearest airport
( )5. A. the radio          
( )6. A. train              
( )7. A. classes            
( )8. A. helps              
( )9. A. helps              
( )10. A. come              
B. looks for        
B. students        
B. station          
B. th e nearest town
B. the farms        
B. ground          
B. meetings        
B. hands            
B. calls            
B. meet            
C. helps with  
C. books        
C. cinema      
C. the big city
C. them        
C. radio        
C. parties      
C. sends        
C. thanks      
C. arrive      
D. thinks about
D. blackboards  
D. school      
D. the capital  
D. it          
D. computer    
D. programs    
D. shows        
D. visits      
D. appear      
单项选择题