when的用法四种句型:be doing sth…when;be about to do sth…when;hardly…when;had just done…when。
1.be doing sth…when
例:He was still smiling when the door opened and his wife came in.
他正笑着的时候门突然开了,他妻子走了进来。
2.be about to do sth…when…
例:We were about to start when it began to rain.
我们刚要出发,天就开始下雨了。
3.had not done sth…when…/hardly…when…
例:He had not fallen asleep when the telephone rang.
他刚要入睡电话就响了。
4.had just done…when…
例:I had just gone to bed after a very hard day when the phone rang.
在劳累了一天之后我刚刚就寝,电话铃就响了。