英語高亮注意（
時間狀語從句
用法
用來在句中充當時間狀語成分。
連接詞
when, while, as, after, before, since, until/not...until,
once, immediately, directly, instantly,
as sonn as, by the time, the moment, the minute,
no sooner ... than, hardly ... when 等。
簡單例句
When you think you know nothing, then you begin to know something.
Strike while the iron is hot.
主要時態：
主現從不限；主過從過；主將從現（重點）；主祈從現；主情從現。
要點
while, when, as比較
when 引導從句的謂語一般是瞬間性動詞，泛用性較強。從句動作和主句動作可以同時發生，也可以先后發生。若是暗示一種規律，那么也用when。
while 引導從句的謂語是延續性動詞，強調某一時間段內主從句動作同時發生，相當於during the time that...。可以表對比（並列連詞）。
as 常用來表示"一邊...一邊..."；還可以用來說明兩種正在發展或變化着的情況，有“隨着”的意思，表示時間的推移。
- 例句
It’s cold when it snows.
I was playing games when he came in.
While/As she was studying, I was playing games.
While we were talking, she came in.
She sang as she went along.
As she grew older, she kept more to herself.
when的幾種句型
(be about to do)/(on the point of doing) when ... 剛要做...時突然...
was/were doing when ... 正在做...時突然...
have/has done when ... 做完了...時突然...
before的幾種用法
It won't be ... before ... 用不了多久就...
It will be ... before ... 還要過多久才...
It wasn't be ... before ... 沒過多長時間就...
It was be ... before ... 過了多長時間以后才...
- 例句
It won't be long before the end of the class.要不了多久就下課了。
It will be a long time for one to gain his own success.一個人要取得成功要很長時間。
It wasn't long before the couple met again.這對夫婦沒過多久就相見了。
It was long before they found their son.過了很久后，他們才找到他們的兒子。
until要點
強調句中多用until而非till, 如果主句謂語是瞬間動詞，那么要用not...until. 如果主句動詞時延續性動詞，那么均可，且常用肯定形式。till不可置句首，until可以。
- 例句
Please wait until I arrived.
I didn't go to bed until(till) my father came back.
It was not until the meeting was over that he began to teach me English.
I worked until he came back. 我工作直到他回來為止。
I didn't work until he came back.我直到他回來才開始工作。
since要點
一般情況下，從句中用一般過去式，主句謂語動詞用現在完成時。
1）since引導的狀語從句的謂語動詞是持續性動詞或表示狀態動詞（如live，stay，study，learn，smoke，be等）的過去時，則從句表示的時間是“從動作或狀態的完成或結束時算起”。
2）since引導的狀語從句的謂語動詞為持續性動詞或表示狀態動詞（如live，stay，study，learn，smoke，be等）的現在完成時，那么since所表示的時間是“從動作開始的那一時刻起”，翻譯時按字面的意思理解即可。
- 例句
I have been in Beijing since you left. 自從你離開以來，我一直在北京了。
It is four years since my sister lived in Beijing. 我妹妹不在北京住有四年了。
She has never come to see me since I have lived in the city.自從我住到城里，她就一直不來看我。
I haven’t heard any noise since I slept. 我醒后還未聽到任何聲音。
Do you know how long it's been since I've grabbed a spoon?你知道自從我拿起勺子多久了嗎？
as soon as要點
類似詞匯：once, immediately, directly, instantly, the moment, the minute, the instant
強調動作的緊隨，注意區分after和when. 即as soon as主句動作緊跟從句動作。
- 例句
As soon as I reach Canada, I will ring you up. 我一到加拿大，就給你來電話。
by the time要點
如果從句中謂語動詞一般過去時，那么主句中的動作常用過去完成時。
如果從句中謂語動詞是一般現在時或者現在完成時（表將來），那么主句中動作常用將來完成時。
如果主句中動作不強調已經完成，那么根據時態選擇。
- 例句
By the time I got to the station, the train had already gone.
By the time I graduate next year, I will have lived here for 5 years.
By the time he went abroad, he was 14 years old.
幾種倒裝
no sooner ... than, hardly when, scarcely ... when結構中主句用過去完成時，從句一般用一般過去時。
且當這些表示否定意義的詞或者短語在句首，主句部分倒裝。