(1) It be adj. (for sb.) to do sth.
例 It is illegal (for a teenager) to drive a car without a license。
(2) It be adj. of sb. to do sth.
例 It's kind of you to help me with the problem.
It's no good/use doing…
It's (well)worth doing…
It's (well)worth one's while doing/to do…
It's (well)worth while doing/ to do
例 It's no use crying over spilt milk.
(1) It is noun 从句
例 It is no secret that the president wants to have a second term at office.
(2) It is adj. clause
It's surprising that? (should)
例 It's important that you should apologize to her for your rudeness
(3) It verb sb. clause= It is v-ing clause
It surprise/delight/interest/disappoint/worry/disturb/annoy/amaze /
bother/concern/frighten/please/anger sb. that…
例 It worried me that she drove so fast.(= It was worrying that she drove so fast.)
(4) It verb (to sb.) that…= sb/sth verb to do
(verb = appear, seem, come about, emerge, follow, chance, happen, occur, transpire, turn out , work out)
例 It (so) happened/chanced that they were out.(= They happened/chanced to be out.)
(5) It is v-ed that…=sb/sth is to do
(verb=say, report, think, believe, hope, expect, agree, accept, decide, determine, intend, plan, understand, know）
例 It is said that the couple have gotten divorced.(=The couple are said to have gotten divorced.)
(6) It is v-ed that … (should)…
(verb=demand, request, require, order, suggest, advise, recommend 例 It is suggested that they should begin with the third question.
1. It takes sb. ? to do?(=sb takes?to do?)某人用多长时间做某事
例 It took the men a week to mend our roof.(= The men took a week to mend our roof.)
2. It's (just)(un)like sb. to do?（不）像某人做某事的风格
例 It was (just) like him to think of helping us.
3. It's (about/high) time that? should /v-ed?是该做某事的时候了
例 It's(about/high) time that we should take action.
4. It's the x-th time (that) ? have v-ed?第几次做某事了
例 It's the third time that he has failed the driving test.
5. It is/has been? since ?continuous v-ed(延续性动词) 某动作已有多长时间不发生了
例 It's 10 years that he lived here
6. It was(not)? before?过(不)了多长时间某动作发生了
例 It was not long before they arrived.
It is/was 被强调部分 that(who)? 强调句型用来强调谓语动词以外的任何句子成 分。当被强调部分是人时也可以用who。
例 When was it that he changed his mind to take part in the activity？
例 It was because he was ill that he didn't come to school yesterday.
3. 在强调not ? until结构时必须把not与until一起放到被强调的位置上
例 It was not until she took off her dark glasses that I realized she was my brother.
例 It was at 7 o'clock that he came here yesterday.( 强调句型)
It was 7 o'clock when he came here yesterday.(定语从句)