It was they that (who) cleaned the classroom yesterday. It was in the street that I met her father.
2. It is not until +被强调的部分+ that
该句型译成汉语“直到……才”，可以说是的强调形式。It was not until she took off her dark glasses that I realized she was a film star. =Not until she took off her dark glasses did I realize she was a film star. =I didn’t realize she was a famous film star until she took off her dark glasses.
3. It is clear (obvious, true, possible, certain) that….
It is very clear that he’s round and tall like a tree.
=That he’s round and tall like a tree is very clear.
4. It is important (necessary, right, strange, natural…) that…
It is important that we (should) learn English well.
It is necessary that he (should) remember these words.
5. It is said (reported, learned…) that…
该句型中的it 仍是形式主语，真正的主语是that 引导的主语从句。该结构常译为“据说（据报道，据悉……）
It is said that he has come to Beijing.
It is reported that another earth satellite has been put into orbit.
6. It is suggested (ordered…) that…
It is suggested that the meeting (should) be put off.
It was ordered that we (should) arrive there in two hours.
7. It is a pity (a shame…) that …
It is a pity that such a thing (should) happen in your class.
It is a pity that he is ill.
8. It is time (about time, high time) that…
It is time that children should go to bed.
=It is time that children went to bed.
9. It is the first (second, …)time that…
10. It is …since…
It is (has been) 5 years since his father died.