It is 被强调部分+ that + 句子其他部分。
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.
He read three books in the library yesterday.
It was he whoread three books in the library yesterday.
It was three books that he read in the library yesterday.
It was in the library that he read three books yesterday.
It was Tom whoI met last week.
It is a new boke that his brother wants to buy.
It is at 5 oclock that the train will arrive.