1)It + is/was + 被强调部分 + that/which/who/whom/whose + 句子的其他成分：
It was uncle Bill、whose telephone number I lost.
It was we that/who arrived there first.
It was because it rained heavily that they didn’t go outing.
误：It is beautiful that Helen is.
Tom is absolutely right in doing this job.
This is just the word the author uses in his article.
He is nothing if not careful.(=He is very careful.)
They are the truest of friends.
The very act stepping on this soil was for me a far greater adventure.
The newspaper reporters got excited at the very sight of the Nobel Prize Winner.
It is beautiful song that Helen is singing.