21. —How much difficulty did you have_____ the problem?
—_____. It’s quite easy.
A. to solve; Nothing  B. to solve; None    C. solving; None    D. solving; Nothing
22. “You can have some cakes, _____ you must wash your hands first.” Mum says.
A. and              B. or                 C. but          D. so
23. This pair of jeans looks nice _____ Sandy, because she looks very nice _____ blue.
A. on; in               B. in; on             C. for; on          D. to; in
24. The twins are in different classes. One is in Class One and_____ is in Class Two.
A. another          B. other              C. the other        D. others