两者在用法上应注意以下几点：
1.相关主句谓语必须是持续性动词,若是终止性动词,则应为否定式（因为终上性动词一旦被否定就成为状态,便可持续）.如：He waited until she was about to leave.他等着一直到她准备离开.She didn’t marry until she was over fifty.她直到50多岁才结婚.
2.引导时间状语从句时,其谓语要用现在时表示将来意义.如：I won’t leave until he comes back tomorrow.我要等他明天回来后再走.Continue in this direction until you see a sign.一直朝着这个方向走就看见指示牌了.
3.有时其后可跟副词或介词短语等.如：He has been ill until recently.他最近一直生病.Until when are you going to stay here?你在这儿要待到什么时候?We didn’t eat till past midnight.直到午夜过后我们才吃饭.She won’t go home until after the exam.她要考完试之后再回家.如果语境的`需要,有时甚至可以接带有“引导词”的从句.如：Don’t leave until after I’ve spoken to you.我和你说完后再离开.