20.Having decided to rent a flat, we　　　 　to contact all the accommodation agencies in

the city.

　 A. set about　　　　　　　　　 B. set down　　　　 C. set out　　　　　　　　　　 D. set up

19.The air in the room was so smelly that he kept the windows 　　　。

　 A. to open　　　　　　 B. open　　　　　　　　 C. opened　　　　　　　　　 D. opening

18. It is quite obvious that 　　　you work hard during the college period, you won’t get an

ideal job after graduation.

A. unless　　　　　　　 B. whenever 　　　 C. although　　　　　　　　 D. if