21. “What do you think made Mary so upset?” “_______ her new bike.”
A. As she lost B. Lost
C. Losing D. Because of losing
22. The research is so designed that once _______ nothing can be done to change it.
A. begins B. having begun
C. beginning D. begun
23. Though ________ money, his parents managed to send him to university.
A. lacked B. lacking of
C. lacking D. lacked in
24. Tony was very unhappy for _______ to the party.
A. having not been invited B. not having invited
C. having not invited D. not having been invited
25. Though I have often heard this song _______. I have never heard you _______ it.
A. being sung, sang B. sang, singing
C. sung, sing D. to be sung, to sing
26. He is a man of few words, and seldom speaks until _______ to.
A. spoken B. speaking
C. speak D. be spoken
28. When I handed the report to John, he said that George was the person _______.
A. to send B. for sending it
C. to send it to D. for sending it to
29. _______ on time, this medicine will be quite effective.
A. Taking B. Being taken
C. Taken D. Having taken
30. The film star walked to his car, ______ a crowd of journalists.
A. followed by B. following by
C. to follow D. to be followed by
【答案与解析】
21. 选C。答句是针对疑问词 what 的回答，而问句中的疑问词 what 在句中用作主语，所以答句也应是一个能用作主语的东西，比较四个选项，只有C合适。其完整回答形式为 Losing her new bike made Mary so upset. 比较，下面一题要填不定式，因为四个选项中只有 To choose a new chairman 能回答疑问词 why：
“Why was a special meeting called?” “______ a new chairman.”
A. Choose B. Choosing
C. To choose D. Chosen
22. 选D。由于 the research 与 begin 是被动关系，故用过去分词 begun。Once begun 可视为 once it is begun 之省略。
23. 选C。由于 his parents 与 lack money（缺钱）是主动关系，故用现在分词，又因为 lack 是及物动词，故后接宾语无需用介词，故选 C。
24. 选D。非谓语动词的否定式要将否定词 not 放在整个非谓语动词之前，据此可排除 A、C。另外，由于 Tony 与 invite 是被动关系，故选 D。
25. C。第一空填 sung，因为 song 与 sing 是被动关系；第二空填 sing，因为 you 与 sing 是主动关系。
27. 选A。until spoken to 可视为 until he is spoken to 之略。
28. 选C，不定式短语to send it to 用作这语，修饰其前的名词 the person。注意句尾的介词 to 不能省略，因为被修饰的名词 the person 为介词 to 的逻辑宾语。
29. 选C。this medicine 与动词take 为被动关系，故用过去分词。
30. 选A。从句意上看，人群跟在明星后面，反过来，明星便是被人群跟着。
