一、利用主动和被动关系

这里说的主动与被动关系，指的是非谓语动词所表示的动作与其逻辑主语之间是主动关系还是被动关系。若是主动关系，非谓语动词就用主动式;若是被动关系，非谓语动词就用被动式。下面分三类举例说明：

1. 涉及不定式的主动与被动式

(1) I feel greatly honored _________ into their society. (北京卷)

A. to welcome B. welcoming C. to be welcomed D. welcomed

答案为C。be (feel) honored后习惯上接不定式，故可排除B和D;又因为I与welcome之间为被动关系，故用不定式的被动式。

(2) The message is very important, so it is supposed _________ as soon as possible. (陕西卷)

A. to be sent B. to send C. being sent D. sending

答案为A。be supposed后习惯上不接动名词，而接不定式，其意为“应该做某事”，故可排除C和D;又因为“消息”与“传达”之间为被动关系，故用被动式。

2. 涉及动名词的主动与被动式

At the beginning of class, the noise of desks _________ could be heard outside the classroom. (全国II)

A. opened and closed B. to be opened and closed

C. being opened and closed D. to open and close

答案为C。由于desks与open和close的关系是被动关系，故要用被动式，可排除D;又因为用于介词of后作宾语，所以要用动名词，不用不定式或过去分词，故可排除A和D，所以答案选C。

3. 涉及现在分词的主动与被动式

_________ that she was going off to sleep, I asked if she’d like that little doll on her bed. (北京卷)

A. Seeing B. To see C. See D. Seen

答案为A。首先要排除B和C，因为B为不定式，它用于句首时，通常是表示目的，在此不合句意;而C为动词原形，选它会构成祈使句，一是句意不通，二是这样会导致前后两句之间没有连词而出错。在剩下的A和D之间，只能选seeing，不能选seen，因为句子主语是 I与see之间为主动关系，而非被动关系。

【注意】由于过去分词本身可以表示被动，所以过去分词不用被动式，同时它也没有被动式。请看几道相关的考题：

(1) The trees _________ in the storm have been moved off the road. (湖南卷)

A. being blown down B. blown down C. blowing down D. to blow down

答案为B。由于trees与blow down之间为被动关系，故要用过去分词。blown down in the storm在此用作定语，修饰the trees，相当于定语从句which were blown down in the storm。

(2) To learn English well, we should find opportunities to hear English _________ as much as we can. (江苏卷)

A. speak B. speaking C.spoken D. to speak

答案为C。由于English与speak之间为被动关系，故要用过去分词。

(3) We finished the run in less than half the time _________. (江西卷)

A. allowing B. to allow C. allowed D. allows

答案为C。由于time与allow之间为被动关系，故要用过去分词。in the time allowed意为“在规定的时间内”。