16--20 A C A A C 21--22 A D 16.It's+形容词/名词 to do sth 【固定结构】 17.in total 词组【一共】 18. forget to do sth 忘记要做某事 19.省略至to为止 20.agree to do sth 同意做某事 21. wh-+不定式 22.why not do sth?为何不....? try doing sth尝试做某事
16. A It is +adj.+(for sb)+to do sth. 17.C in total 总共 18. A forget to do 不要忘记去做某事儿 19.C tell sb (not) to do 20. C agree to do 21. A 22. D why not do sth