1. 从方框中选择合适的连词完成句子

because   unless   when   so…that   since  as…as…  until  though  while   if

1. （1） It's hard for us to say goodbye we have so many happy days to remember
3. （2） He waited she had finished speaking.
5. （3） Mr Black walked around and offered help we were doing an experiment.
7. （4） His clothes, old and worn, looked clean and of good quality.
9. （5） You mustn't drive a car on the road you get a driver's license.
11. （6） I have lived in New York I was 11 years old.
13. （7） it is rainy tomorrow, I will stay at home.
15. （8） The manager of the hotel was waiting at the gate the guests arrived.
17. （9） Little John is cute everyone likes him very much.
19. （10） My swimming pool is not big yours.