when的意思:1,什么時(shí)候,用于提問(wèn),如:When did you last see him?
2,在那時(shí),用于時(shí)間的表達(dá)方式之后,如：Sunday is the only day shen I can relax.
3,在……之后,如：Call me when you have finshed.
4,一……就……,如：He had just drifted lff to sleep when the phone rang.
5,當(dāng)……時(shí)候,如：When I was young,I had a lovely cat.
until的意思：到……時(shí),到……為止,如：Let us wait until the rain stops.