问题 问答题

小明和小华一起探究“凸透镜成像的规律”,他们分别用f1=l5cm和f2=10cm的凸透镜做实验,下表是他们记录的部分数据

像的性质焦距f/cm试验序号物距u/cm像距v/cm
倒立、缩小154023
3527
104013
3514
由这部分数据可初步发现

(1)若以“透镜的焦距为单位”进行比较,在成倒立、缩小的像时:物距(u)与焦距(f)的关系是______;像距(v)与焦距(f)的关系是______.

(2)成倒立、缩小实像时:物距减小,像距______;若物距相同,焦距大,像距______.

答案

(1)凸透镜成倒立、缩小的实像时,u>2f,2f>v>f.

(2)成倒立、缩小实像时:

由实验序号①和②(或③和④)得,焦距相等,物距减小,像距增大;

由实验序号①和③(或②和④)得,物距相同,焦距越大,像距越大.

故答案为:(1)u>2f;2f>v>f;

(2)变大;越大.

完形填空
完形填空
                                                     The Pecan Thief
     When I was six years old,  I was visiting my grandfather' s farm in Kansas.Grandpa had sent me into
the  1   to gather pecans for us to enjoy later.

     Pecan picking was really  2   work and my little basket was only half full.I wasn' t about to_3_
Grandpa down.Just then something caught my  4  . A large brown squirrel was a few feet away.I
watched as he picked up a pecan,  hurried to a tree and   5   in a large hole in the trunk.A moment
later the squirrel   6   out and climbed down to the ground to pick up another nut.Once again,  he took
the pecan back to his hiding place.
      Not so  7   anymore,  I thought.I dashed over to the tree and looked into the hole.It was  8   with
pecans!Golden pecans were right there for taking.This was my  9  . Handful by handful,  I scooped all
of those pecans into my basket.Now it was full! I was so  10   of myself.I couldn' t wait to show Grandpa
all the pecans.  11  ,  I ran back and shouted,  "Look at all the pecans!" He looked into the basket and
said,  "Well,  well,  how did you find so many?" I told him how I' d  12   the squirrel and taken the pecans
from his hiding place.
      Grandpa congratulated me on how smart I' d been in observing the squirrel and his habits.Then he did
something that  13   me.He handed the basket back to me and put his arm gently 14   my shoulders.
     "That squirrel worked very hard to gather his winter  15   of food,  " he said."Now that all of his pecans
are gone,  don' t you think that little squirrel will  16   the cold winter?"
     "I didn't think about that,  " I said.
     "I know,  " Grandpa said."But a good man should never take  17   of someone else' s hard work."
     Suddenly I felt a bit  18  .The image of the starving squirrel wouldn't  19   my mind.There was only one
thing I could do.I carried the basket back to the tree and poured all the nuts into the hole.
      I didn't eat any pecans that night,  but I had something much more filling-the   20   of knowing I had
done just the right thing.
( )1. A. rooms  
( )2. A. hard  
( )3. A. let  
( )4. A. sweater  
( )5. A. joined  
( )6. A. jumped  
( )7. A. strange  
( )8. A. covered  
( )9. A. time
( )10. A. afraid  
( )11. A. Otherwise  
( )12. A. driven  
( )13. A. annoyed  
( )14. A. off  
( )15. A. supply  
( )16. A. escape  
( )17. A. place
( )18. A. guilty  
( )19. A. open  
( )20. A. inspiration
B. woods        
B. dirty        
B. settle      
B. basket      
B. lived        
B. held        
B. secret      
B. filled      
B. choice      
B. a shamed    
B. However      
B. followed    
B. satisfied    
B. beside      
B. cost        
B. spend        
B. notice      
B. unconfident  
B. leave        
B. expectation  
C. holes  
C. light  
C. have    
C. eye    
C. discovered  
C. stood  
C. anxious  
C. rebuilt  
C. chance  
C. careful  
C. Besides  
C. protected  
C. surprised  
C. over    
C. support  
C. survive  
C. advantage  
C. embarrassed    
C. cross  
C. impression  
D. roads            
D. easy            
D. keep            
D. hand            
D. disappeared      
D. found            
D. patient          
D. decorated        
D. achievement      
D. proud            
D. Therefore        
D. caught          
D. delighted        
D. around          
D. preparation      
D. flee            
D. charge          
D. nervous          
D. occupy          
D. satisfaction    
单项选择题