Scientists do not know why dinosaurs became extinct, but some theories postulate that changers in geography, climate, and sea levels were responsible.
It is/ was + 被强调部分(通常是主语、宾语或状语)+ that/ who(当强调主语且主语指人)+ 其他部分。
It was yesterday that he met Li Ping.
Was it yesterday that he met Li Ping?
被强调部分(通常是疑问代词或疑问副词)+ is/ was + it + that/ who + 其他部分
When and where was it that you were born?
4) not … until … 句型的强调句
A. 句型为：It is/ was not until + 被强调部分 + that + 其他部分
普通句：He didn't go to bed until/ till his wife came back.
强调句：It was not until his wife came back that he went to bed.
此句型只用until，不用till。但如果不是强调句型，till, until可通用;因为句型中It is/ was not ... 已经是否定句了，that后面的从句要用肯定句，切勿再用否定句了。
A. It is/ was ... that ... 结构不能强调谓语，如果需要强调谓语时，用助动词do/ does或did
Do sit down. 务必请坐。
Do be careful when you cross the street. 过马路时，务必(千万)要小心啊!
Do write to me when you get there.
How dare you buy such expensive jewels?
I really don’t know what to do next.
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?
How interesting a story it is!
Why!why!The cage is empty!
On the table were some flowers.桌上摆着一些花。(强调地点)
It was on Monday night that all this happened.
If anyone knew the truth，it was Tom.
It’s because of hard work—ten years of hard work.
It was because the water had risen that they could not cross the river。
Authority is a postulate of the moral order and derives from God.
The school building programme postulates an increase in educational investment.
____ that caused him to serve dinner an hour later than usual.（典型高考陷阱题）
A. It was we being late
B. It was our being late
C. It was we were too late
D. It was because we were late