64. 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

【解析】 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。

63. 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

【解析】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。

62. Though ________ money, his parents managed to send him to university.

A. lacked                                                         B. lacking of

C. lacking                                                        D. lacked in

【解析】 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。

61. The research is so designed that once _______ nothing can be done to change it.

A. begins                                                         B. having begun

C. beginning                                                    D. begun

【解析】 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。

60. “What do you think made Mary so upset?” “_______ her new bike.”

A. As she lost                                                  B. Lost

C. Losing                                                        D. Because of losing

【解析】 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。

59. “How do you deal with the disagreement between the company and the customers?” “The key ______ the problem is to meet the demand ______ by the customers.”

A. to solving, making                                       B. to solving, made

C. to solve, making                                          D. to solve, made

【解析】 B。the key to… 意为“……的关键”，其中的 to 是介词，不是不定式符号，若后接动词要用动名词。另一方面，名词 demand 与 make 是被动关系(make demands 提出要求)，同时根据句中的 by the customers，可确定答案选 B。

58. Finding her car stolen, _______.

A. a policeman was asked to help                       B. the area was searching thoroughly

C. it was looked for everywhere              D. she hurried to a policeman for help

【解析】D。非谓语动词作状语时，其逻辑主语就是句子主语。比较四个选项，finding her car stolen 的逻辑主语显然是 she，而不是 a policeman, the area, it 等，故选 D。

57. A cook will be immediately fired if he is found _______ in the kitchen.

A. smoke                                                         B. smoking

C. to smoke                                                     D. smoked

【解析】B。find 后可接现在分词（表示动作在进行）或过去分词（表被动关系）作宾语补足语，但是不接不定式。另外，由于he 与 smoke 是主动关系，故选 B。

56. The boy wanted to ride his bicycle in the street, but his mother told him _______.

A. not to                                                         B. not to do

C. not do it                                                      D. do not do

【解析】 A。不定式的否定式总是将否定词 not 置于不定式符号 to 之前，而不能置于其后，同时结合 tell sb (not) to do sth 这一结构可排除选项 C、D。当不定式的动词是前面已出现过的相同的动词时，为避免重复，通常省略该不定式而只保留不定式符号 to。

55. We looked everywhere for the keys, but they are nowhere _______.

A. to find                                                        B. to have found

C. to be found                                                  D. being found

【解析】C。因keys 与 find 是被动关系。