when词性有副词、介词、连词和名词四种。
when，英语。
[英][wen] [美][wɛn]
adv.什么时候 （用于时间的表达方式之后）在那时 其时 当时
conj.在…时 既然 如果
pron.什么时候 那时
n.时间，时候 日期 场合。
扩展资料
1、[adv.]
(1)[疑问副词]什么时候，何时，在什么情况下
用于疑问句首，如 When do you begin your classes?
(2)从前，以前当年: When you were a child， you didn't know what it means.
(3)在……时候：His wife always complains when he smoke.
(4)[关系副词]彼时，其时:Where when he knows wrong， he doesn't admit.
2、[conj.](常用于连接两件事)
(1)什么时候：He told us when to eat.
(2)届时，在那时：He came at six， when the sun was setting.
(3) 是……的时候了：He came at a time when we needed help.
(4)当……时，在……的时候：When we are at college.
(5)每逢，每当：She smiles when you praise her.
(6)相反，而，却：To complain of one's lot when one might change it.(本来可以改变自己的命运，却自怨命苦。)
(7)既然，鉴于：How can he help when they won't let him.
3、[pron.]
什么时候(常用于定语从句)：It was in the morning， when he died.
4、[n.]
时间：When in doubt， leave out.
when doing中when的词性
when做连词时加句子，做介词时加动名词，所以这种情况的when是介词