1. It + be + adj. + (for sb) to do sth → sth + be + adj. + to do
It is not easy to learn English. (English is not easy to learn.)
备用词：difficult, necessary, important, quick, hard, etc.
2. It + be + adj. + of sb to do sth → sb. + be + adj. + to do sth
It was foolish of Tom to sell such a suit as that to a millionaire.
(Tom was foolish to sell such a suit as that to a millionaire.)
备用词：wise, clever, bright, kind, nice, silly, stupid, cruel, etc.
3. It takes sb + some time + to do sth → sb spends time in doing sth
It took him two days to find the elephant.
(He spent two days in finding the elephant.)
4. It is no use doing sth.
It is no use regretting your past mistakes.
备用词：no good, useless, etc.
5. It costs sb. + money + to do sth
It cost them 36,000 francs to buy the necklace.
→ The necklace cost them 36,000 francs .
They spent 36,000 franc on the necklace.
They spent 36,000 francs (in) buying the necklace.
They paid 36,000 francs for the necklace.
They bought the necklace for 36,000 francs.
6. It + be + adj. (n.) + that-clause
It is very clear that he’s round and tall like a tree.
It is a pity that she has made such a mistake.
备用词：natural, surprising, true, wonderful, etc.
7.It + be + adj. + that-clause (should do sth)
It is necessary that he (should) be present at the meeting.
8. It + be + p.p. + that-clause
it is said that he has been ill for years. (He is said to have been…)
备用词：reported, known, believed, decided, announced, etc.
9. It + be + p.p. + that-clause (should do sth.)
It is demanded that the homework (should) be finished at once.
备用词：ordered, suggested, required, requested, etc.
10. It seems + that-clause → sb. + seems + to do sth.
It seems that they are talking. (They seem to be talking.)
11. It is + some time since-clause → sb. has + p.p. + for time
It is three years since he came here. (He has been here for years.)
12. It is + 被强调部分 + that (who)
It is through struggle that we learn this truth.
13. It + be time + for sth / to do sth. / that-clause
It is time for supper. It is time to have supper.
It is time that we should have supper.
It is time that we had supper.
14. It + be + long(时间段）+ before-clause
It will not be long before we turn our hope into reality.
15. It is (just) like sb. to do sth.
It’s like him to leave the work to others.
It isn’t like him to have said anything like that. 他可不是说出那种话的人。
16. It is up to sb. to do sth.