英文句子有主句和子句，以从属连接词为首的子句，补充说明主句的意义，可以表示时间、原因、条件和对比等。从属句在前的时候，要用逗号隔开。从属连接词在后的时候，则不用。
表示时间的连接词: after / before / when / while / as soon as / as long as / so long as / since / until / as
after 在…之后
After I get home from work, I like to sit down in my favorite chair to read the newspaper in peace and quiet.
我在下班回家后，喜欢坐在最爱的椅子上安静地看报纸。
Jane went to work after she had breakfast.
Jane在吃过早餐后去上班
before 在…之前
Check your report carefully before you hand it in.
在你交出去之前，要仔细检查你的报告。
Think over what I said before you make your decision.
在你做出决定前，认真考虑我所说的话。
when 当…时候
When Jessica comes here tomorrow, give this book to her.
当Jessica明天来这里的时候，把这本书给她。
We were all tired and hungry when the basketball was over.
当篮球赛结束的时候，我们全部都又饿又累。
while 当…时候
Wendy found many old photos while she was cleaning out her room.
当Wendy那时在清理她的房间时，她找到了很多老照片。
While I was walking down the street, I ran into an old friend of mine.
当我那时走在街上时，我巧遇了一位老朋友。
as soon as 一…就…
As soon as I saw my son, I knew something was wrong.
我当时一见到我儿子，我就知道什么事不对劲了。
Call me as soon as you get there.
你一到那里的时候，就打电话给我。
as long as 只要
We are very happy for you to stay at our house as long as you like.
只要你喜欢，我们非常乐意你留在我们家。
As long as you work hard, you can make it.
只要你努力，你就可以做得到。
so long as 只要
You can borrow my car so long as you don’t drive too fast.
只要你不要开得太快，你可以借我的车。
It’s OK to fail so long as you learn from your mistakes.
只要能从错误中有所学习，失败没有关系。
since 自从
I’ve been very busy since I came back from holiday.
自从我度假回来就非常地忙碌。
Since Judy moved to Japan, we haven’t heard from her.
自从Judy搬到日本，我们就没有听到她的消息了。
until 直到…时候
I will stay here until you come back.
我会待在这里直到你回来。
Jane didn’t go to bed until her daughter came home last night.
Jane 昨天晚上直到她女儿回家才上床睡觉。
as 当…时候
I saw John as I was coming into the building.
当我那时进入大楼时，我看到了John。
Mr. Jennings gets more attractive as he gets older.
随着年龄的增长，Jennings 先生变得愈发有魅力。
