1. as, while , when的区别
as引导的时间状语从句, 可以表达“正当……”， “一 边……一边……”，“随着……”等意思。
1. 表示某事一发生，另一事立即发生。 As the sun rose, the fog disappeared.
2. 表示在某事发生的过程中，另一事发生。 Just as he was speaking there was a loud explosion.
until/ till引导的时间状语从句
◆ until / till 引导的时间状语从句，常译为“直到……时”， 表示主句动作发生在从句之前。 ◆当主句谓语动词是延续性动词时，主句常用肯定形式。
He likes pop music, while I am fond of folk music.
when: 持续性／非持续性动词都可
＊当……时
e.g. When I first saw her, I fell in love with her. ---When did you get home? ---It was eight o’clock when I got home.
状语时用来修饰 动 词， 形容 词， 副 词或 句子 的一种句子成分。它可以表示时间、地点、 原因、目的、结果、条件、让步、比较、方式等。 当充当状语的部分是一个句子时，也就是状语从
句。分类如下：
状语从句
1. 时间状语从句 2. 地点状语从句 3. 原因状语从句 4. 条件状语从句 5. 让步状语从句 6. 目的状语从句 7. 结果状语从句 8. 方式状语从句 9. 比较状语从句
After you use plastic bags, you mustn’t throw them about. 用过了塑料袋之后，不准到处乱扔。
since引导的时间状语从句
◆ since引导的时间状语从句，常译为“自从……”， 主句常用现在完成时，从句常用一般过去时。 例句翻译：我们自从分手以后一直没见过面。
We haven’t seen each other since we parted. 常用句型：It has been (is) + 时间段 + since从句
“自从……有多长时间了 ”
例句翻译：自从她大学毕业已经有六年时间了。 It has been (is) six years since she graduated from the university.
3. 表示两个动作同时发生。 Helen sang a song as she washed.
4. 表示“随着…..”.常指一个行为是另一个行为的结果， 或一种状态随另一种状态变化。句中的动词多表示状态 的发展变化。As she grew older, she became more beautiful.
e.g. He walks when he might take a taxi. 虽然
The Queen will visit the town in May, when she will open the new hospital. 届时
How can you hope for mercy yourself when
while:持续性动词 ／进行时
＊一般或现在情况
e.g. I like listening to music while I am doing现在进行时
e.g.— I’m going to the post office. -- While you are there, can you get some stamps for me?
While I really don’t like art, I find his work impressive. ( while =_a_l_t_h_o_u_g_h_ )
While there is life there is hope. (while = __a_s_l_o_n_g_a_s_ )
引导词可分为两部分．
as while when whenever before after until (till) since as soon as
every time next time the first/…time the moment the minute/… instantly immediately directly (一…就…)
＊过去情况
e.g. I hurt my should while I was doing gym.
While 在句中的不同含义:
While I was walking down the street, I came across an old friend. ( while=__w_h_e_n__)
We clean the classroom before we leave school every day. It will not be long before you regret for what you’ve done. 不久你就会为你的所作所为后悔的。
after引导的时间状语从句
◆ after引导的时间状语从句，常译为“在……之后”， 表示主句的动作发生在从句的动作之后。
you show none?
如果
How could I live in Los Angeles when all my
favorite people live here? 鉴于, 既然
before引导的时间状语从句
◆ before引导的时间状语从句，常译为“在……之前”， 表示主句的动作发生在从句的动作之前。
＊正在……忽然
1) They were walking down the street when they saw 2) an accident. 2) I was about to go swimming when our guide stopped
me.
when 还有一些较为灵活的翻译:
＊尽管／虽然／鉴于／如果／届时／