动词不定式有两种被动式, 即一般式和完成式, 例如do的被动式有to be done, to have been done。只有及物动词和相当于及物动词的短语才有不定式的被动式。一般说来, 当不定式的逻辑主语是不定式动作的承受者时, 该不定式要用被动式。例如:
He asked to be sent to work in that factory. 他要求派他去那个工厂工作。
These books are not allowed to be taken out of the room. 这些书不许带出室外。
但在某些情况下, 不定式虽然表示被动意思, 用的却是主动形式。常见的有下列几种情况:
一、在某些固定句型中, 动词不定式作定语, 用主动形式表被动意义。
1）have（give, show）sth. to do
在这种句型中的不定式与前边的名词有动宾关系, 又和句中另一名词或代词构成主谓关系。例如: I have a lot of things to do this afternoon. to do与things是动宾关系, 与I是主谓关系。否则, 在表示被动意义时, 仍需要被动式。试比较:
Have you anything to do this afternoon? 今天下午你有事要做吗?
（to do是由you发出的）
Have you anything to be taken to your parents? 你有要带给你父母的东西吗? （谁带不得而知）再如:
Please get me something to read. 请给我弄点读的材料。
He'll show you the right path to take. 他会给你指出要走的正确的路。
2）It（This, That）＋be＋a／an＋adj. ＋ n. ＋to do
在这种句型中, 不定式与前面的名词有动宾关系。动词不定式可改为动词不定式复合结构。例如: This is a difficult question to answer. 这是个难答的问题。
question与to answer为动宾关系。to answer可改为 for me to answer。再如:
It is an easy sentence to translate. 这个句子很容易翻译。
3）There ＋be ＋n. ＋to do
在此句型中, 用来修饰主语的不定式, 可用主动式, 也可用被动式, 只是侧重点不同。用主动式作定语, 重点在人, 用被动式作定语, 重点在物。例如:
没有时间可以耽误。可译成:
There is no time to lose（to be lost）. 用 to lose可看成for us to lose; 用to be lost, 谁 lost time不明确。
但下述两句用主动不定式与被动不定式意义不同:
a. There is nothing to do now. （＝We have nothing to do now. ）现在没事干。
b. There is nothing to be done. （＝We can do nothing now. ）现在没办法了。
a. There is nothing to see. （nothing worth seeing）没有东西值得看。
b. There is nothing to be seen. （nothing there at all）看不见什么东西。
二、在某些“形容词＋不定式”的结构中, 不定式有被动意义, 与句子主语构成动宾关系。其句型有:
1）n. ＋be＋adj. ＋to do
The question was very difficult to answer. 这问题很难回答。
The job is very easy to do. 这工作很容易做。
2）n. ＋be＋too＋adj. ＋to do
The thing is too small to see. 这东西太小看不见。
I was too excited to say a word. 我激动得连一句话也说不出。
3）n. ＋be ＋adj. ＋enough to do
The box is light enough to carry. 这盒子轻得可带走。
The book is cheap enough to buy. 这本书很便宜可以买。
但下列两句可用不定式的主动式, 也可用被动式:
This plant is fit to eat ／to be eaten. 这种植物可以食用。
The cake is ready to eat ／to be eaten. 这块饼可以吃了。
三、某些动词, 如to let, to blame （责备）, to seek（寻找）用主动式表被动意义。
例如:
The house is to let. 这房子要出租。
Who is to blame for it? 这得怪谁?
The reason is not far to seek. 这理由不难找到。
练习: 选择填空。
1. The chair looks rather hard, but in fact it is very comfortable to __________.
a. sit b. sit on c. be sat d. be sat on
2. I'm hungry. Get me something __________.
a. eat b. to eat c. to be eat d. for eating
3. It is difficult for a foreigner __________ Chinese.
a. write b. to write c. to be written d. written
4. I have no more letters __________, thank you.
a. to type b. typing
c. to be typed d. typed
5. The car is rather difficult __________.
a. to repair b. to be repaired
c. repairing d. being repaired
6. He was nowhere __________.
a. to see b. to be seen c. seeing d. seen
7. She had no money __________ a birthday present for their children.
a. to buy b. to be bought c. bought d. buying
8. We waited for the work __________.
a. done b. being done c. to do d. to be done
