7. when 容易与时间状语从句混淆的例子
请注意：此项中when引导的都不是时间状语从句。
She had just finished dressing when her guests came in.
她刚刚穿戴完毕，这时她的客人进来了。
这里的when不是从属连词，而是并列连词。所以它引导的是并列句。像这类问题有以下主要特征：
when 后面的分句动词必须是瞬间动词，用于表示突然性：
We were about to start when it began to rain.正当我们要出发的时候，突然下雨了。
1).when 前面的分句是过去进行时：
He was still smiling when the door opened and his wife came in.
他正笑着，突然门开了，他的妻子走了进来。
2).when 前面的分句含有be about to, be on the point of:
He was on the point of leaving when someone knocked at the door.
他正要出发的时候，突然有人敲门。
3).when 前面的分句采用过去完成时或是过去完成进行时：
We had just fallen asleep when the telephone rang.
我们刚刚入睡，突然电话铃声响了。
The plane had been planting seed for nearly a month when it began to rain.
飞机播种了近一个月，这时天才下雨。
