当不定式的逻辑主语是不定式动作的宾语或承担者时，这个不定式要用被动语态。(一般时态通常表示将来的动作;完成时态表示发生在谓语之前的动作)。不定式的被动形式在句中可以用作主语、表语、宾语、主补语、宾补语、定语、动名词等。
1.用作主语。例如：
It is an honour for me to be invited to the party.我被邀请参加晚会，这是个荣幸的事。
2.用作表语。例如：
Nothing seems to have been forgotten.仿佛一切都记忆犹新。
The problem remains to be further discussed in detail.这个问题尚需进一步详细讨论。
3.用作宾语。例如：
She asked to be sent to our college.她请求派到我们学院。
The students wanted to be given more experiments to do.学生们想多给些实验做。
More than half a century after his death，he continues to be read and quoted.他去世已经半个多世纪，他的著作继续为人们阅读和引用。
4.用作主语补语。例如：
Transistors are known to be widely used in radio industry.晶体管被公认广泛用到无线电工业中。
This book is said to have been translated into English.据说这本书已经译成英语。
5.用作宾语补语。例如：
He did not like his intention to be laughed at.他不喜欢自己的意图受到嘲笑。
6.用作定语。例如：
This question will be discussed at the conference to be held next month.这个问题将在下月举行的会议上讨论。
Let us show you the engine to be tested.让我们给你看看要检验的那台发动机。
7.用作状语。例如：
1 was glad to have been praised.我很高兴受到了表扬。
He has returned only to be sent away again.他回来后又被派了出去。
