21. While the dog, you should take care not to . otherwise, is may put strangers in danger.
A. walking; let it loose B. walk; be loose C. walking for; get it loose D. training; get it run
22. Knowing the result of the exam, he went home and lay in bed, .
A. upset B. was upset C. felt upset D. and upset
23. Jane is so interested in computers that she likes everything them.
A. like B. such as C. doing with D. to do with
