问题 问答题

一个铜球质量是89g,体积是20cm3,问:

(1)该球是空心的还是实心的?

(2)若在空心部分注满水,总质量是多少?

答案

(1)∵ρ=

m
V
,铜的密度ρ=8.9g/cm3

∴质量为m=89g实心铜球的体积为

V0=

m
ρ
=
89g
8.9g/cm3
=10cm3<铜球实际体积V=20cm3

所以此球是空心的.

(2)空心部分体积V'=V-V0=20cm3-10cm3=10cm3

∵ρ=

m
V
,∴注入水的质量mV′=1g/cm3×10cm3=10g,

总质量m=m+m=89g+10g=99g;

答:(1)铜球是空心的;

(2)在空心部分注满水,总质量是99g.

完形填空
完形填空。
    When I was a little boy, I would play outside for hours on sunny summer days and then have a deep
and peaceful sleep at night. Sometimes, I'd have some vivid dreams, making me   1   for a moment. I
would stare out into the darkness to see if anything was there and then   2   over and go back to sleep.
I can still remember a few times when I woke up,   3   out into the darkness, and actually   4   someone
there. It was
     Mom   5   over me as I slept. Each time she   6   told me to go back to sleep and I closed my eyes
again, feeling   7    and loved.
     I   8    asked Mom why she watched me sleep from time to time, but   9   seeing my own children 
  10   so fast, I think I know why. She wanted to catch a moment in time and   11   it in her heart forever.
I just   12   that she carried a lot of those moments with her into Heaven when she  13   at only 55.
    Last night I was sleeping lightly   14   I suddenly felt someone near me. I opened my eyes and saw
Mom's   15   standing in the room, smiling at me. And then she was gone.
Now   16   may say that this was just a dream, a wish or part of an old   17   . To me, though, it was 
  18   that Mom's loving spirit was still watching over me. To me, it was evidence enough to know that
one day I would be   19   with her and everyone I have ever loved.
    Trust in their love. Know that your own life can be full of   20   , too. Then joyfully go out and live it
with a brave heart and a smiling soul.          
( )1. A. excited
( )2. A. take  
( )3. A. went   
( )4. A. met    
( )5. A. watching
( )6. A. angrily
( )7. A. quiet  
( )8. A. never  
( )9. A. before
( )10. A. bring up
( )11. A. hold  
( )12. A. decide
( )13. A. ran away
( )14. A. when  
( )15. A. body  
( )16. A. all
( )17. A. dream
( )18. A. proof
( )19. A. reunited
( )20. A. hope  
B. afraid  
B. roll
B. burst
B. saw
B. treating
B. gladly
B. nervous
B. often
B. after
B. raise up
B. remove
B. hope
B. put away
B. while
B. figure
B. none
B. wish
B. time
B. buried
B. joy
C. worried
C. look
C. looked
C. expected
C. helping
C. silently
C. safe
C. sometimes
C. since  
C. lift up
C. find
C. wonder
C. passed away
C. after
C. shape
C. some   
C. story
C. chance
C. connected
C. love
D. awake    
D. climb    
D. found    
D. dreamed  
D. sitting  
D. gently    
D. anxious
D. seldom    
D. for      
D. grow up  
D. cover    
D. remember  
D. took away
D. before    
D. shadow    
D. any      
D. memory    
D. belief    
D. joined    
D. surprise  
判断题