when可当疑问副词,也可当关系副词.
1.when当疑问副词,一定是放在句首.
例:When is the play going to start?这场戏什麼时候要开始?
2.when当关系副词,用来修饰表时间的先行词,可用来代替"时间介系词+which",如" at which,in which"
例:Do you remember the day THAT I invited you out?记得我邀你出去的那一天吗?
=Do you remember the day WHEN I invited you out?
=Do you remember the day ON WHICH I invited you out?
=Do you remember WHEN I invited you out?(这里的when引导名词子句作受词用)
3.when(当.) 主要用於强调事情发生的时间.用在句首或句中意思并没有差别
例:When her name was called,she stood up.
= She stood up when her name was called.
叫她名字的时候,她站了起来.
但注意,when在句首,两个句子之间要用逗号隔开,when在句中,就是一个句子.
