句型11
It強調(diào)句型
強調(diào)句的基本構(gòu)成：It is/was + 被強調(diào)的部分 + who(主要指人時)/that + 其余部分
[注意1]
這種結(jié)構(gòu)可以強調(diào)句子的主語、賓語、狀語(包括時間，地點，方式，原因等)，但是不能強調(diào)謂語動詞(參考句型15)。
原句的謂語動詞如果是現(xiàn)在或?qū)頃r態(tài)，用It is…that/who….;
原句的謂語動詞如果是過去時態(tài)，用It was…that/who….;
強調(diào)時間、地點、原因或方式時不要用when, where或how, 必須用that。
[例句1]
I saw him in the street yesterday afternoon.
→It was I who saw him in the street yesterday afternoon.(強調(diào)主語)
→It was in the street that I saw him yesterday afternoon.(強調(diào)地點狀語)
→It was yesterday afternoon that I saw him in the street.(強調(diào)時間狀語)
→It was him that/who I saw in the street yesterday afternoon.(強調(diào)賓語)
[例句2]
He didn't go to bed until his mother came back.
→It was not until his mother came back that he went to bed.
He didn't do his homework until his father came back from work.
→It wasn't until his father came back from work that he did his homework.
[例句3]
Only when you nearly lose someone do you fully realize how much you value him.
→It is only when you nearly lose someone that you fully realize how much you value him.
只有你快要失去某個人時，你才意識到你是多么尊重他。
[例句4]
I was late again because the traffic was very heavy during the rush hour.
→It was because the traffic was very heavy during the rush hour that I was late again.
(強調(diào)句中只能強調(diào)由because引導(dǎo)的原因狀語從句，because不能換成since, as, for, now that等)
[注意2]
強調(diào)句的疑問結(jié)構(gòu)
一般疑問句 Is / Was it +被強調(diào)部分 +who / that …?
特殊疑問句 特殊疑問詞+is /was +it +who / that…?
What is/was it that…? Who is/was it that…? When is/was it that…?
Where is/was it that…? Why is/was it that…? How is/was it that…?
[例句1]
I saw him in the street yesterday afternoon.
→When was it that you saw him in the street?
→Who was it that you saw in the street yesterday afternoon?
→Where was it that you saw him yesterday afternoon?
[例句2]
I don't know when he will come back.
→I don't know when it is that he will come back.(賓語從句疑問詞后用陳述句語序)
—How was it that you got in touch with Mr. Smith? 你是怎么和Smith先生聯(lián)系上的?
—Trough a friend of mine. 通過一個朋友。

句型12
(1)祈使句(表條件)+ or/or else/ otherwise + 主句(表結(jié)果)… "否則…，要不然…"
(2)祈使句(表條件)+ and +主句(表結(jié)果)
[例句]
Hurry up, or you'll be late for class.
Please call me up before you come, otherwise/or else/or we might be out.
你來之前打個電話，否則，我們也許會出去。
Think it over and you will find the answer.
Give him an inch and he will take a mile. 得寸進(jìn)尺。
Work hard and you will make progress every day. 好好學(xué)習(xí)，天天向上。

句型13
…until…"直到……時候";not…until…"直到……才……"
[例句]
You are to stay until/till your mother comes back. 你得等到你媽媽回來。
The meeting was put off until ten o'clock. 會議推遲到十點鐘。
The villagers didn't realize how serious the pollution was until all the fish died in the river.
→Not until all the fish died in the river did the villagers realize how serious the pollution was.(倒裝句)
等到湖里的魚全死光了，村民們才意識到污染是多么嚴(yán)重。
He didn't go to bed until his mother came back.
→It was not until his mother came back that he went to bed.(強調(diào)句)
Not until he failed in the exam did he realize that he had wasted much time playing computer games.
Not until his son came back from school did he go to bed.

句型14
unless…"除非，如果不……"(=if…not)
[例句]
I shall go tomorrow unless it rains. 如果不下雨，我明天去。
—Shall Tom go and play football?
—Not unless he has finished his homework. 除非他完成作業(yè)，否則不能出去。
I won't go unless he comes to invite me himself.
除非他本人來邀請我，不然我是不會去的。
I won't attend his birthday party unless invited (=unless I am invited). 除非被邀請，否則我不去參加的生日晚會。

句型15
when引導(dǎo)的從句
when除了用來引導(dǎo)主語從句、賓語從句、時間狀語從句、表語從句和定語從句，還有一種用法值得關(guān)注，那就是when引導(dǎo)并列分句，意思是"這時突然;就在那時"，強調(diào)另一個動作的突然發(fā)生。常用于以下句型中：(1)主語 + be doing… when…意思是"正在做某事這時……";(2)主語 + be about to do…when…;(3)主語+be on the point of (doing) …when…意思是"正要去做某事這時……"
[例句]
One day Chuck was on a flight across the Pacific Ocean when suddenly his plane crashed. 有一天，Chuck正在太平洋上飛行，這時他的飛機突然爆炸了。
I don't know when he will arrive. 我不曉得他什么時候到達(dá)。
I thought of the happy days when I was in Beijing. 我想起了在北京時的那段快樂日子。
I believe the time will soon come when there will be no weapons in the world. 我相信世界上沒有武器的日子不久就會到來。
I was walking along the river when I heard a drowning boy cry for help. 我正在河邊行走，這時我突然聽到一個落水男孩求救。
I was about to leave when it began to rain. 我剛要離開，這時下雨了。
I had just finished my exam paper when the bell rang, announcing the class was over. 我剛做完作業(yè)，下課鈴響了。
I thought of the happy days when I was in France. 我想到了在法國時那段快樂日子。
[比較]
I was walking along the street when I caught sight of a tailor's shop. 我正在街上走，這時我看見一家裁縫店。
I was walking along the streets. Just at the moment I caught sight of a tailor's shop. 我在街上走。就在那時我看見一家裁縫店。