20. ------The windows must have taken you quite a long time that day.

　 ------ Right. They _____ for weeks.

A. haven’t been cleaned　　　　　 B. didn’t clean

C. hadn’t been cleaned　　　　　 D. haven’t cleaned　　　

19. It’s important to weigh all ____ information to find out the truth of what is reported.　

A. suitable　　 B. relevant　　 C. satisfactory　　 D. proper