1. 表原因
I was very glad to be invited. 我很高兴被邀请。
I'm pleased to have been given this opportunity. 给了我这次机会我很高兴。
2. 表目的
I had to shout to be heard. 我必须叫喊对方才能听得见。
She was sent to England to be educated. 她被送到英国去受教育。
As she waited to be served, she became very impatient. 她在等候侍者送饭时，很不耐烦。(G12)
3. 表结果
You were lucky not to be killed. 你大难不死，真是好运气。
I had to shout to be heard. 我必须叫喊对方才能听得见。
注意以下特殊结构：
(1) only to be done结构
He has returned only to be sent away again. 他回来后又被打发走了。
She got there only to be told that they had gone on holiday. 她到达那里，被告知他们度假去了。
(2) too…to…结构
The case was too heavy to be carried by a child. 箱子太重小孩拿不动。
He was too young to be entrusted with such a task. 他年纪太轻不宜委以这样的任务。
(3) so as to结构
He shut himself in the room so as not to be disturbed. 他把自己关在屋里以免受到打扰。
