A. has, been on      
B. had, begun                
C. had, been on

A. is reading            
B. have read            
C. will read

A. broke    
B. have broken    
C. was broken

A. was happening    
B. to happen            
C. has happened

1. He             (enjoy) every year of junior high school.
2. Don't forget______ (close) the windows when you leave the classroom.
3. Would you please   ____  (not sit) on the desk?
4. Mr Li   _____ (teach) here since 1987.
5.  He would never think of______(let) his daughter marry a fellow like you.

1. Trees must __________(prevent) from being cut down.
2. They __________(plant) ten thousand trees by last spring.
3. The sheep __________(tie) to the tree has eaten a lot of grass.
4. I can easily hear combs __________(go) through hair.
5. Great changes __________(take) in our hometown in the last ten years.

A. is wrong    
B. isn't work    
C. has broken down

A. Has, cleaned        
B. Has, been cleaned  
C. Was, cleaned

1. She's already done her homework. (改为否定句)
    She____ ____ her homework _____.
2. She has borrowed the book. She borrowed it from the library last week. (改成同义句)
    She ____ ____ the book for a week.
3. I bought the bike ten years ago. (改成同义句)
    I ____ ____ the bike _____ ten years ago.
4. There were few books in the desk, _____ _____? (反意疑问句)
5. It no longer provides a good environment. (改为同义句)
    It                   a good environment                  .
6. You are too young to go to school. (改为同义句)
    You are ____ ____ ____ you can't go to school.
7. I've known him since he came him. (对划线部分提问)
    _____ ____ _____ you known him?
8. There was heavy rain yesterday evening. (改成同义句)
    It _____ _____ last night.
9. My father was a teacher in the past. (改为同义句)
    My father                    be a teacher.
10. I saw the film 2012 just now. (用just做状语)
      I _____ just _____ the film 2012.

A. worked
B. works
C. is working
D. has worked