1、XB2U4 GrammarHilda你学过哪些你学过哪些it作形式主语的句式？作形式主语的句式？it it 作形式主语的用作形式主语的用法？法？主语部分相对于谓语部分而言太长，常把主语部分移到句尾，在主语主语部分相对于谓语部分而言太长，常把主语部分移到句尾，在主语位置放上位置放上it。it 没有具体的意义，仅用于维持句子结构平衡，避免主语太长，显得没有具体的意义，仅用于维持句子结构平衡，避免主语太长，显得头重脚轻。头重脚轻。it作形式主语主要有三种情况：代表作形式主语主要有三种情况：代表不定式不定式作形式主语、代表作形式主语、代表动名词动名词作形式主语、代表作形式主语、代表从句从句作形式主语。
2、作形式主语。it it 代表不定式作形式主语代表不定式作形式主语 It is impossible to get there by boat.It is difficult for a foreigner to learn Chinese.It is kind of you to help me.It+be+adj.+to do sth.It is adj.for sb.to do sth.&It is adj.of sb.to do sth.两者区别？两者区别？adj.描述人的品质、品格，介词用描述人的品质、品格，介词用of；adj.描述不定式所表示动作的特描述不定式所表示动作的特征，介词用
3、征，介词用for。it it 代表不定式作形式主语代表不定式作形式主语 It was her duty to clean the room.It is not a good habit to stay home too late.It+be+n.+to do sth.it it 代表不定式作形式主语代表不定式作形式主语 It was against my principle to do that.It+be+p.p.+to do sth.p.p.=prepositional phraseit it 代表不定式作形式主语代表不定式作形式主语 It cost 150 yuan to buy the
4、 dress.It took the workers almost three years to finish building them.It+vt.+O.+to do sth.vt.=transitive verb O.=Object it it 代表不定式作形式主语（小代表不定式作形式主语（小结）结）It+be+adj.+to do sth.(for&of 区别区别)It+be+n.+to do sth.It+be+p.p.+to do sth.It+vt.+O.+to do sth.it it 代表动名词作形式主语代表动名词作形式主语 常用于以下结构中：常用于以下结构中：It+be+a
5、dj.+doing sth.It is pleasant sitting here.It+be+n.+doing sth.其中常见结构有：其中常见结构有：It is no use/no good/no fun/useless/a waste of time doing sth.做某事没有用做某事没有用/没有好处没有好处/没有意思没有意思/没有用没有用/浪费时间。浪费时间。It is no use crying over spilt milk.=It is useless crying over spilt milk.覆水难收。覆水难收。it it 代表从句作形式主语代表从句作形式主语 it代表
6、的从句可以用代表的从句可以用that来引导，也可以用来引导，也可以用whether/if、连接代词或连、连接代词或连接副词引导。接副词引导。It is obvious that students should get well prepared for their future.It is doubtful whether she will be able to come.It is a mystery to me how it all happened.it it 代表从句作形式主语代表从句作形式主语 It is natural that she knows everything about
7、 it.It is necessary that the work should be done.It+be+adj.+that.it it 代表从句作形式主语代表从句作形式主语 It is a pity that you didnt see such a good film.It is our hope that in coming decades,advances in science will offer new perspectives from which to study how people manage their lives.It+be+n.+that.常见于：常见于：It
8、is a pity/a shame/a fact/an honour/good news/no wonder/a wonder/.+that.it it 代表从句作形式主语代表从句作形式主语 It is said that nothing has been done about it.It is hoped that the number of deer will greatly increase very soon.It+be done+that.常见于：常见于：It is said/reported/believed/hoped/known/suggested.+that.据说据说/据报道
9、据报道/大家都相信大家都相信/人人都希望人人都希望/大家都知道大家都知道/有人建议有人建议 It is suggested/ordered/required.(表坚持、建议、命令、要求的动表坚持、建议、命令、要求的动词词)that S.+(should)do sth.(S.=Subject)It is suggested that the meeting _be_(be)put off.it it 代表从句作形式主语代表从句作形式主语 It may be/seems that he views the issue from a different perspective.It seemed t
10、hat I had become what my parents had wanted me to be.It+be/其他系动词其他系动词+that.it it 代表从句作形式主语（小代表从句作形式主语（小结）结）It+be+adj.+that.It is a pity/a shame/a fact/an honour/good news/no wonder/a wonder/.+that.It is said/reported/believed/hoped/known/suggested.+that.It+be/其他系动词其他系动词+that.it it 作形式主语的其他固定句作形式主语的其
11、他固定句型型 It turns(ed)out that.结果是结果是 It turns out that the situation is quite serious.It occurs(red)to sb.that.某人突然想起某人突然想起 It occurred to her that she might adopt a homeless child.It doesnt matter whether/if.是否是否没关系没关系 It doesnt matter if you miss the bus,because theres another one 15minutes later.It looks/seems as if.好像好像 It looks as if he is wrong.It takes/took sb.(some time)to do sth.It took us three hours to get there.THANK YOU
