21. ——tom, you are caught late again.
——oh, ____.
a. not at all b. just my luck c. never mind d. that's all right
答案: b just my luck是习语，意思为“真倒霉！”。not at all和that's all right多用于对方感谢时的应答语，“不客气”。never mind用于对方道歉时的应答语，“没关系”。
22. ——what do you think of the concert?
——i really enjoy it. i didn't expect it was ____ wonderful.
a. as b. more c. most d. very
答案: a 这是一个省略句，承接上文，省略了as i had thought。
23. the engineers made two big plans for the dam, ____ was never put in force.
a. one of them b. which c. one of which d. every one of which
答案: c 本题主要是对句子结构及关系是考查。根据逗号可知，后面句子为非限制性定语从句，先行词是plan；再根据句子中的was及前面的two可知本题的正确答案为c。
24. i have no one ____ me, for i am a new comer here.
a. help b. helping c. to help d. to have helped
答案: c 本题主要考查非谓语动词的用法。根据句意可知句子空白处的非谓语动词作定语，用have sb. /sth. to do的结构。
25. the little girl couldn't work the problem out. she wasn't ____ clever.
a. that b. much c. enough d. too
答案: a 本题主要是对副词的考查。that作副词时，相当于so，强调所指的某一程度；much作副词时，一般只用来修饰形容词或副词的比较级及动词；enough作副词时，总是用在谓语所修饰的形容词或副词之后；too作副词时，强调事物的程度已超出某范围，让人难以应付。
26. listen! his family must be quarrelling, ____?
a. mustn't it b. isn't it c. aren't they d. needn't they
答案: c 本题主要考查反意疑问句的表达方式。根据listen可知，must be quarrelling表示推测，此时反意疑问句中的动词须依主语而定，由于his family是指他家里的人，故be用复数形式。
27. the police have ____ power to deal with such matters by ____ law.
a. the; the b. 不填；不填 c. 不填；the d. the；不填
答案: d 本题主要考查冠词的用法。句子第一空后面的不定式做定语对power进行修饰，特指某种权力，用定冠词the；而第二空后面的law泛指“法律”这一概念，不用冠词。
28. jack felt unhappy as they all went outing ____ him.
a. except b. but c. without d. besides
答案: c 本题主要考查介词的用法区别。根据句子中的felt unhappy可知，句子中表示一种心理状态，于是，正确答案为c。
29. that she hadn't kept her ____ on her work resulted in the failure.
a. head b. heart c. brain d. mind
答案: d 本题主要考查名词的意义区别。根据后面的resulted in failure可知，她没有专心于工作，而keep one's mind on意思为“专心于”，于是正确答案为d。
30. ——did your sister pass the exam?
——she failed and is in low spirits.
——i'm sorry for her.
——____.
a. thank you b. you're welcome c. i would think so d. never mind
答案: a 本题主要考查英语交际用语的应用。根据对方的话“i'm sorry for her”表示对她的关心，于是回答应该用“谢谢”，因此正确答案为a。