形式主语是一个代词

1、个IT,就是形式主语”可是楼主所举的句子能换位吗？从表面上看，第一句话说成“Who didthe experiment in the lab yesterday evening was my fa ther.好像没有什么语法错误， 但是这里却 存在致命的逻辑错误。如果句子主语是Who引导的主语从句，那么动作的发出者就成了我爸爸（who是连接代词）昨晚在实验室里做实验”注意：我爸爸昨晚在实验室做实验”这是一件事，可不是一个人，所以后面怎么能接“was my father呢”如果这样写，那么句子直译过来就是我爸爸昨晚在实验室里做实验是我爸爸。"这语言是不是很后现代？那么这句话能不能改对呢

2、？答案是能，而且可以改得非常漂亮，非常地道，只要加一个代词就可以了，我把它改成 “ He who did the experiment in the lab yesterday evening was my father.（顺y便说一句，虽然很多人，也包括绝大多数老师，都喜欢与The man who，但是有央文阅读习惯的人一般都认为He/Shewho 的表达更加地道，当然前者也没有任何错误。）发现了么？这么一改，“ Who引导的从句就成了 定语从句，而句子的主干则成了 “ He was mfather.，逻辑错误消失了。问题2:这里的问题和上面完全一致，所以楼主能把这两个问题捆绑起来提冋也很咼

3、明。what做连接词的时候永远等于thething（s） that，那么如果用1what的话，显然就是把句子当成形式主语IT引导的句子，而不是 强调句了，于是它可以把主语还原，变成“Thething that attracted the audienee's interest was how the young man haclearned five f oreign Ianguages.，而这句话显然是正确的。于是，冋题变成了为什么一疋要把这句话看成强调句，而不能把它当成IT作形式主语呢？ 答案是，因为如果不掉过来，这句话是错的。我们退回一步，用取简单的方式还原，这句话成了It wa

4、s how the you ng manhad lear ned five foreig n Ian guages the thi ng that attracted the audie nee's in terest.楼主，这话通顺吗？是不是很别扭？能告诉我别扭在哪里吗？这话别扭在，IT作形式主语只能代名词性结构（从名词性短语、动名词、名词性从句），它代不了名词+定语从句的结构。怎么改？在问题1中，我们添了个主语， 把主语从句变成了定语从句，这里我们反其道而行之， 给它去掉主语“the thing，把定语从句还原回主语从句，于是，强调句的结构就出现了。所以归根结底，强调句和IT作形式

5、的主语的区别是什么？是that/who所引导的句子是能够独立作主，还必须修饰别人的区别；如果能够独立从当主语而不会出现逻辑错误，那它就是IT作形式主语；反之，必须通过添主语的方式把它改造成定语从句，让它修饰新添加的主语句子逻辑上才能通顺，那它就是强调句。第一部分常规主语从句，即句子在复合句中充当一个 主语主语从句的时态：不受主句的时态影响和限制。（1）That he finished writing the eomposition in such a short time surprised us all.（2）Whether we will go for an outing tomorrow

6、 remainsI T 9 !H> WMRM 巴 W 4-ih feafN- ife liW IPw 1 |1管 lA Ifajr*k3nDrrs nanaM.ll> w h w14* wwh *> I !. fc WW.wM hbm uhbwk* 利!>1耳IW M4| ElI” WWI Hwunknown.（3）Who will be our mon itor has n't bee n decided yet.（4）Whom we must study for is a question of great importanee.（5）What caused

7、 the aeeide nt rema ins unknown.（6）Whatever you did is right.（7）Who the watch belongs to was lost is unknown.（8）What we n eed is time.（9 ） What we n eed are good doctors.小结（1）引导主语从句连词有that,whether,who,what,whatever 等（2）连词位于句首不能省略（3 ）主语从句大多数情况下视为第三人称单数，但也有例外，如例（9 ）为了防止句子头重脚轻，通常把形式主语it放在句首位置，真正主语搁置于句末

8、（1）It is certain that he will win the match.（2）It is true that he has made a very important discovery in chemistry.（3 ） It is very likely that they will hold a meeti ng.（4 ） It is stra nge that he should do that.（5 ） It is important that we all should attend the meeting.（6 ） It is strange that the m

9、an should have stuck to his silly ideas.（7 ） It is a pity that we won't be able to go to the south to spe nd our summer vacatio n.（8 ） It is still a mystery what caused the accide nt.（9 ） It is said that he has gone to sha nghai.（=He is said to have gone to sha nghai）（10）It is known to all that

10、the gun powder was first inven ted by the Chin ese.（11）It is suggested that the work should be done with great care.（12）It happe ned that the two cheats were there. （=The two cheats happe ned to be there）小结:（1） 为避免头重脚轻，常以形式主语it引导从句。lt+形式主语谓语+从句。（2） 由于主语从句一般被认为是单数形式，形式主语的谓语动词、be动词+表语 均 为单数第三人称形式或过去式.

11、主语从句的用法绍。一.主语从句主语从句 定义：在句子中担当主语的是一个从句，这个从句就叫做主语从句。主语从句是在复合句中充当主语的从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。1. It作形式主语和it引导强调句的比较 主语从句常用it作形式主语，一般常用句型为：It is+名词/形容词/过去分词+主语 从句例如：It is still a question whether she will come or not.It is stra nge that you should like him.It is still unknown which team will w

12、in the match.另外，还有一些比较多见的结构：It turned out that ；It has bee n proved that ；It happe ned/occurred that ；It is well- known that 等等 而强调句则不同，它的结构是： It+be+被强调部分+that+从句强调主语：It is the times that produce their heroes.时势造英雄强调宾语：It is En glish that Prof.L in teaches us.强调状语：It was in sha nghai that I saw the

13、film.判断是否是强调句有一个方法，就是将that以后的句子的其余部分”拿出来单独看，看有没有缺成分，缺的是什么成分，再把谓语动词后面that前面的那部分，带到你认为缺成分的地方，如果放进去是一句 完整的句子了，那就说明是强调句。2. 用it作形式主语的结构It is + 名词+that从句It is a fact that 事实是It is an honor that 非常荣幸It is com mon kno wledge that-是常识(2) it is + 形容词+that从句It is natural that很自然It is stran ge that 奇怪的是(3) it +

14、不及物动词+that从句It seems that 似乎It happe ned that 碰巧it is+ 过去分词+that从句It is reported that 据报道It has been proved that已证实 3主语从句不可位于句首的五种情况(1) if引导的主语从句不可居于复合句句首。(2) It is said , (reported)结构中的主语从句不可提前。例如：It is said that Preside nt Jingo will visit our school n ext week.(3) It happe ns ,It occurs结构中的主语从句不可

15、提前。例如：It occurred to him that he failed in the exam in ati on.It doesn' t matter how/whether结构中的主语从句不可提前。例如：It doesn ' t matter whether he is wrong or not.(5)含主语从句的复合句是 疑问句时，主语从句不可提前。例如:Is it likely that it will rain in the eve ning?4. What与that在引导主语从句时的区别What引导主语从句时在从句中充当句子成分，如主语宾语表语，而that则

16、不然。例如：What you said yesterday is right.二：宾语从句用以区分主语从句的几个特征：1、引导词:whatwhichwhosewhenwhetherifwhere2语序：宾语从句必须是用陈述语句。如: I think that you must work harder.宾语从句的引导词、 连接词的区别、否定转移 等现象。(1) 表达时间的几个句型：一般用 when或者是what time :What time will the train leave?由于时刻都是固定的，也可以用一般现在时代替一般将来时：What time does the train leave?(2) 时间的表达方式：8： 19(nineteen past eight),7:57(three to eight) ，在时间的中间也可以加上分的单词 (mi nu tes)(3) had better +动词原型。意思是提要求，建议。但是上下级不能用这种方式，因为语 气太重：You had better give up smok ing .(4) sb leave sth + 地点