1. 单句改错，每句有一处错误，指出并改正

1. （1） If your news station or school requires interviewers to sign release forms to appear on the air, don't leave work without them.
   
3. （2） There stand an old tree on the top of the hill.
   
5. （3） He is in a dangerous situation where he doesn't know how to deal with.
   
7. （4） You'll be faced with two choices—whether to be fired or not, depend on your performance in the work.
   
9. （5） You'd better put on a thick sweater in case of it snows.
   
11. （6） My parents don't approve me making friends with him.
    
13. （7） It is demanded that a doctor must be sent for.
    
15. （8） He didn't notice his mother enter his room with his attention concentrating on the computer games.
    
17. （9） I need my brother's approval of use his bike.
    
19. （10） He found he could no longer cope with his demanded job.