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