中考英語語法知識點：介詞和連詞(2)
6.從屬連詞
從屬連詞用來引導從句。常見的從屬連詞有：
(1)引導時間狀語從句的after, before, when, while, as, until, till, since, as soon as等。(2)引導條件狀語從句的if, unless等。
(3)引導原因狀語從句的because, as, since等。
(4)引導目的狀語從句的so that, in order that等。
(5)引導讓步狀語從句的though, although, even if等。
(6)引導結果狀語從句的so that, so…that, such…that等。
(7)引導比較狀語從句的than, as…as等。
(8)引導名詞從句的that, if , whether等。
7.常用連詞的用法辨析
(1)while, when, as
這三個連詞都可引導時間狀語從句，但用法有所不同。
1)當某事正在進行的時候，又發生了另一件事。While, when, as 都可用來引導表示“背景”的時間狀語從句。例如：
As/When/While I was walking down the street I noticed a police car.
2)當兩個長動作同時進行的時候，最常用的是while。例如：
While mother was cooking lunch, I was doing my homework.
3)當兩個動作都表示發展變化的情況時，最常用的是as。例如：
As children get older, they become more and more interested in things around them.
4)當兩個短動作同時發生時，或表示“一邊…一邊…”時，最常用as。例如：
Just as he caught the fly, he gave a loud cry.
She looked behind from time to time as she went
5)當從句的動作先于主句的動作時，通常用when。例如：
When he finished his work, he took a short rest.
6)當從句是瞬間動作，主句是延續性動作時，通常用when。例如：
When John arrived I was cooking lunch.
(2)as, because, since , for
這四個詞都可表原因，但用法有區別。
1)如果原因構成句子的最主要部分，一般用because。因此，because引導的從句往往放在句末。例如：
I stayed at home because it rained.
---Why aren’t you going?
---Because I don’t want to.
2)如果原因已被人們所知，或不如句子的其它部分重要，就用as或since。Since比as稍微正式一點。As和since 引導的從句一般放在句子的開頭。例如：
As he wasn’t ready, we left without him.
Since I have no money, I can’t buy any food.
3)for用來補充說明一種理由，因此，for引導的從句幾乎可以放在括號里。For引導的句子不放在句子的開頭。例如：
I decided to stop and have lunch----for I was feeling quite hungry.www.zhongkao5.com//
(3)if, whether
if和whether都可作“是否”講，在引導賓與從句是一般可互換。例如：
I wonder whether (if) you still study in that school.
I don’t know whether (if) he likes that film.
在下列情況下，只能用whether,不能用if：
1)引導主語從句時。例如：
Whether he will come to the party is unknown.
2)引導表語從句時。例如：
The question is whether I can pass the exam.
3)在不定式前。例如：
I haven’t made up my mind whether to go there or not.
(4)so…that, such…that
1)so…that中的so是個副詞，其后只能跟形容詞或副詞，而such…that中的such是個形容詞，后接名詞或名詞短語。例如：
I’m so tired that I can’t walk any farther.
It was such a warm day that he went swimming.
2)如果在名詞之前有many, much, little, few時，用so,不用such。例如：
He has so little education that he is unable to get a job.
I have had so many falls that I am black and blue all over.
(5)either…or…， neither…nor, not only…but also…
這三個連詞詞組都可連接兩個并列成分。當它們連接兩個并列主語時，
謂語動詞要隨相鄰的主語變化。例如：
Either you or he is wrong.
Neither he nor his children like fish.
Not only the teacher but also the students want to buy the book.
(6)although, but
這兩個連詞不能用在同一個句子中。例如：我們不能說“Although he is
over sixty, but he works as hard as others.”這個句子應改為：Although he is over sixty, he works as hard as others.或He is over sixty, but he works as hard as others.
(7)because, so
這兩個連詞同樣不能用在同一個句子中。例如：我們不能說“Because John
was ill, so I took him to the doctor.” 這個句子應改為Because John was ill, I took him to the doctor.或John was ill, so I took him to the doctor.
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