before 表示在一段时间之前。
回家之前我必须干完所有的活。I must finish all the work before go home .
在想要跑以前，你得先学会走。You must first learn to walk before you try to run .
他去伦敦之前已学了三年英语。He had learned English for three years before he went to London .
提示：before 从句往往带有否定的含义。
我还没来得及阻止他，他就跑掉了。He ran off before I could stop him .
趁着还没忘记的时候就记录下来。Take it down before you forget it .
before 常用句型 it is+ before或者it was+ before或者it will be+ before。
五年以后我们才能再见。It will be five years before we meet again .
不用过多久你就会对你所作所为感到后悔的。It will be not long before you regret what you have done .
不久我就意识到我错了。It was not long before I realized I was wrong .
过了几分钟警察才到。It was minutes before the police arrived .
after表在一段时间之后。
放学后我们踢足球吧。Let's play football after school is over .
暴风雨过后不久，太阳出来了。The sun came out soon after the storm stopped .
until或者till 用于肯定句时，表示直到为止，主句必须为持续性动词。
我们将一直等到他回来。 We shall wait until he comes back .
We shall wait till he comes back .
直到发生那意外之前，一切都正常。Everything went well until that accident happened .
Everything went well till that accident happened .
not+ until或者not+till 表示直到才，主句通常要用短暂动词，这时 until 和 till 可用 before 代替。
直到她回来，我才离开的。I didn't leave until she came back .
I didn't leave till she came back .
I didn't leave before she came back .
铃不打不响。Bells don't ring till you strike them .
Bells don't ring until you strike them .
人们直至失去了健康才知其可贵。People do not know the value of their health till they lose it .
People do not know the value of their health until they lose it .
People do not know the value of their health before they lose it .
当 not until 位于句首时，主句中的主语、谓语要使用倒装语序。
直到她不哭了，我才离开的。Not until she stopped crying did I leave .
注意：until 引导的从句可以放在主句之前或主句之后，但 till 从句一般不放在句首。
在强调句型中一般只能用until，不用till。
直到她摘下墨镜，我才认出她。It was not until she took off her dark glasses that I recognized her .
since 自，以来。表示动作从过去某一点时间一直延续到说话时间为止。主句中通常为延续性动词的现在完成时， since 从句中一般用短暂性动词的一般过去时。
我们到这儿刚刚一星期。it has been just a week since we arrived here .
自上次我见过你之后，你去了哪里？Where have you been since I last saw you?
她自年轻时起就一直集邮至今。Since she was young, she has been collecting stamps .
有时 since 从句中也可以用延续性动词，注意它的译法。
汤姆现在农场上班，他上大学已有两年了。Tom is now working on the farm . it's two years since he was a college student .
早餐以后已经过了很长时间了。It's a long time since breakfast.
ever since 从那时起，直至现在，此后一直。表示说话者强调主句动作或状态持续时间长，语气比 since 强。
自一九五零年结婚以来，他们一直过得很幸福。Ever since they got married in nineteen fifty they have lived happily .
since 还可以用作副词或介词。
这只大钟在战争中损坏了，从此就一直不响了。The big clock was damaged during the war and has been silent ever since .
The big clock was damaged during the war and has been silent since .
我叔叔五十年代就去了西藏，从那以后他一直生活在那里。My uncle went to Tibet in the nineteen fifties . He has been living there ever since.
My uncle went to Tibet in the nineteen fifties . He has been living there since .
你们自毕业以来已经在工作中取得了巨大成就。You have made great achievements in your work since graduation .
as soon as 可译为，一，就，用来表示主从句的动作是紧接着发生的。
他一有空就来看你。He will come and see you as soon as he can .
他一得到这个好消息就奔回家。He rushed home as soon as he got the good news .
一，就，可以用 on 或者upon+ doing 结构来表示。
他一到家就给莱斯特打电话。On arriving home, he called up Lester .
as soon as he arrived home, he called up Lester .
immediately 或者instantly 或者directly相当于 as soon as ，从句中用一般过去时态。
他一到家马上就给她打了电话。They phoned her immediately they reached home .
我一看见她就把她认出来了。I recognized her instantly I caught a glimpse of her .
我们一接到你的电话就赶来了。We came directly we got your telephone .
the moment或者 the minute 或者 the instant或者 the second这几个名词短语也可用作连词，直接引导时间状语从句，表示一，就。
他说他一到家就打开电视机。He said he would turn on TV, the moment he got home .
告诉他，他一到我就要见他。Tell him I need to see him, the minute he arrives .
铃一响，学生就冲出了教室。The second the bell rang, the students rushed out of the classroom .
hardly 或者scarcely +when和 no sooner+ than都表示刚，就，可以互换，主句通常用过去完成时。
他刚出发就想起家来。He had no sooner started out than he felt homesick .
他刚开始发言，就有人站起来反驳他的论点。He had hardly started his speech when someone rose to refute his points .
当 hardly或者 scarcely或者 no sooner位于句子的开头时，主句须用倒装语序。
她刚要睡着，忽然敲门声把她吵醒。Hardly had she fallen asleep when a knock at the door woke her up .
地上的霜一消散，人们就开始工作了。No sooner was the frost off the ground than the work began .