21.
（a） the back of his french dictionary fell apart when he dropped it.
（b） he had read the novel without help earlier in the fall.
（c） he needed to look up some words in order to comprehend the novel.
（d） his french teacher helped him with the vocabulary.
22.
（a） go to a movie.
（b） work in the library.
（c） visit a museum.
（d） spend some time outdoors.来源：www.examda.com
23.
（a） there's not enough time to finish.
（b） the clock isn't working.
（c） the report will be ready on time.
（d） he can begin the work at five.
24.
（a） she would rather watch television than go to the theater.
（b） s he doesn't like to go out in the evenings.
（c） she's never been to the theater before.
（d） she wants to watch some television before she goes out.
25.
（a） her umbrella is broken, too.
（b） she needs to use her umbrella.
（c） she'll get her umbrella out of the closet.
（d） she already loaned her umbrella to someone.
26.
（a）george doesn't think sam will win.
（b）sam isn't a strong competitor.
（c）george looks as strong as ever.
（d）sam is going to win the race.
27.
（a） she has a lot of energy.
（b） she's amusing.
（c） she should spend more time on her studies.
（d） she's thinking of giving up her job.
28.
（a） the old coat isn't worth repairing.
（b） he can repair the hole in the coat.
（c） he just saw the woman's new coat.
（d） the woman should take something for her cold and sore throat.
29.
（a） open a savings account.
（b） get a better job.
（c） put more effort into his work.
（d） ask for a raise in salary.
30.
（a） she has already heard the lecture.
（b） dr. crown gave her some assistance.
（c） she can use cathy's notes later.
（d） cathy will give the lecture instead.
