强调句是一种修辞, 是人们为了表达自己的意愿或情感而使用的一种形式, 下面简单归纳它的几种结构: 

1. 用助动词"do（does／did）＋动词原形"来表示强调: 
He does know the place well.
他的确很熟悉这个地方。
Do write to me when you get there.
你到那儿后务必给我来信。

2. 用形容词very, only, single, such等修饰名词或形容词来加强语气: 
That's the very textbook we used last term.
这正是我们上学期用过的教材。
You are the only person here who can speak Chinese.
你是这里唯一会讲汉语的人。
Not a single person has been in the shop this morni ng.
今天上午这个商店里连一个人都没有。
How dare you buy such expensive jewels?
你怎么敢买这么贵的宝石呢?

3. 用ever, never, very, just等副词和badly, highly, really等带有－ly的副词来进行强调: 
Why ever did you do so?
你究竟为什么要这么做?
He never said a word the whole day.
一整天, 他一句话也没说。
You've got to be very, very careful.
你一定得非常、非常小心。
This is just what I wanted.
这正是我所要的。
He was badly wounded.
他伤得很严重。
I really don't know what to do next.
我的确不知道下一步该怎么做。

4. 用in the world, on earth, at all等介词短语可以表达更强的语气（常用于疑问句）: 
Where in the world could he be?他到底会在哪儿?
What on earth is it?它究竟是什么?
Do you know at all?你到底知不知道?

5. 用感叹句来表示强烈的感情, 突出说话人的情感: 
How interesting a story it is!这是一个多么有趣的故事啊!
Oh, what a lie!啊, 真是弥天大谎!

6. 用重复来表示强调: 
Why!why!The cage is empty!
啊!啊!箱子是空的。
They walked for miles and miles.
他们走了好多英里。

7. 用倒装句（也就是将要强调的句子或被强调的部分置于句首）来加强语气: 
On the table were some flowers.
桌上摆着一些花。（强调地点）
Many a time have I climbed that hill.
我多次翻过那座山。
Only in this way, can we solve this problem.
只有这样, 我们才能解决这个问题。

8. 用If来表示强调: 
1）If从句＋I don't know who／what, etc. does／is／has, etc. ; 主语部分也可以用nobody does／is／has, etc. 或everybody does／is／has, et c. 来代替（这里的if从句往往是正话反说, 反话正说）: 

If he can't do it, I don't know who can.
要是他做不了这件事, 我不知道还有谁能做。（强调只有他能做）
If Jim is a coward, everybody is.
要是吉姆是个胆小鬼, 那么人人都是胆小鬼。（强调吉姆不是胆小鬼）

2）if从句＋it be主句（此用法可看成是第8中强调句型的变形, 即把所要强调的内容放在it be的后面, 把其它内容放在由if引导的从句中）: 

If anyone knew the truth, it was Tom.
如果说谁了解事实的真相, 那便是汤姆。
If there is one thing he loves, it is money.
如果说世界上还有他爱的东西, 那便是金钱。

9. 用破折号、黑体字也可以表示强调, 加强语气: 
It's because of hard work—ten years of hard work.
那是因为艰苦的工作--十年艰苦的工作!
He began the work in late May.
他在五月底开始的这项工作。（强调时间）

10. 用强调句型: "It is（was）＋被强调的部分＋that（who）＋原句其它部分"来强调说话人的意愿: 
It was on Monday night that all this happened.
所有这一切发生在周一晚上。
It's me that he blamed.
他怪的是我。

常考的强调句结构是it 引导的句子。
It is (was) 被强调部分+ that (who) + 句子其他部分。
此结构强调的成分仅限于主语, 宾语和状语。
It is from the sun that we get light and heat.
It was not until I had read your letter that I understood the true state of affairs.

当需要强调句中的主语、宾语、状语时, 我们常用"It is(was)+被强调部分+that(who)"这种句型, 使用此句型时, 应注意以下几点。

(1) 一般情况用It is(was)……that…如:
He read three books in the library yesterday.
我们分别可以强调主语、宾语、地点状语和时间状语。如:
It was he who(that)read three books in the library yesterday. (强调主语)
It was three books that he read in the library yesterday. (强调宾语)
It was in the library that he read three books yesterday. (强调时间状语)

(2) 当被强调部分指人时, 可用that, 也可用who; 指物时, 只用what, 如:
It was Tom who(that)I met last week.
It is a new boke that his brother wants to buy.

(3) 强调状语时, 只用that, 不用when、where. 如:
It is at 5 o'clock that the train will arrive.

(4) 被强调的部分是主语时, 注意句子的谓语动词和被强调的主语保持一致。如:
It is he who is late. 　It is they that were late.

(5) 一般疑问句的强调句为"Is (was) it + that…?"; 特殊疑问句为: "特殊疑问词+ is (was) +that…?"结构。如:
Was it ten years ago that his father died?
他的父亲是十年前去世的吗?
When is it that you will set off?
你到底什么时候出发?

(6) "not…until…"句型的强调结构为"It is not until…that…"应注意把否定词not转移到until前面。如:
I didn't go home until rain stopped.
直到雨停了我才回家。
强调句为: It was not until rain stopped that I went home.
I didn't know the news until yesterday.
直到昨天我才知道那个消息。
强调句为: It was not until yesterday that I knew the news.

11. 典型例题
1） It was last night ___ I see the comet.
A. 　the time　B. 　when　 C. 　thatD. 　which
答案C. 强调句的结构是: It +be +强调部分 + that (who) + 主谓句。　强调句的连词只有两个, that和who。当强调的部分是人, 且为句子的主语时, 才用 "who", 其余用that。
原句: 　My father did the experiment in the lab yesterday evening.
强调主语: It was my father who did the experiment in the lab yesterday evening.
强调宾语: It was the experiment that my father did in the lab yesterday evening.
强调时间: It was yesterday evening that my father did the experiment in the lab. (注意不用when)
强调地点: It was in the lab that my father did the experiment yesterday evening.

2）It is ten years ___ Miss Green returned to Canada.
A. that　B. when　 C. since　 D. as
答案C. 考点是连词用法。 本题易误选为A. that. 其实本句不是强调句。若是, 去掉It　 be… that还应是一个完整的句子。而本句去掉 'It is…that', 只剩下ten years Miss Green returned to Canada. 不成句。因此本句不是强调句。
It is /was +时间+ since…　其中is<---> has been　 was <---> had been.