知识点1:表语从句的用法
表语从句
在复合句中作表语的从句叫表语从句。引导表语从句的关联词与引导主语从句的关联词大致一样，表语从句位于连系动词后，一般结构是“主语+连系动词+表语从句”。可以接表语从句的连系动词有：be, look, remain, seem等。注意：关联词不能省略，并且从句用陈述语序。例如：
[1]主语从句,注意,相关知识点if不能引导主语从句。上句中it是形式主语，其后的从句才是真正的主语从句。要注意以下各种情况不宜用if而要用whether:［误］ It is unknown if he will come.［正］ It is unknown whether he will come.［析］ if不能引导主语从句。上句中it是形式主语，其后的从句才是真正的主语从句。要注意以下各种情况不宜用if
The fact is that we have lost the game. That is why he didn't come to the meeting.
[2]that,fact,相关知识点the fact that…引导主语从句the fact that…引导主语从句在许多情况下，当语义上需要用一个较复杂的that从句用主语时，若直接将其置于句首位置，则会显得“头轻脚重”。这时，我们通常采用的办法便是使用形式主语it来改变句子结构。如：That he had no girl friends worried his parents a lot.= It worri
需要注意的，当主语是reason时，表语从句要用that引导而不是because。但是reason 后面的定语从句可以用why 或that引导。例如：The reason why he was late was that he missed the train by one minute this morning
[3]that,定语从句,相关知识点that / those 用作先行词时定语从句用什么引导1. that用作先行词时定语从句用什么引导that后接定语从句时，通常用关系代词which来引导。如：I have that which you gave me. 我有你给我的那个。That which many people say is not always true. 很多人说的并不表示一定是真的。注：that w
【附加】在名词性从句中that与what的区别:
[4]名词性从句,名词,相关知识点人称代词it除了可以指人指物之外,还可以表示“时间、天气、温度、距离、情况”等含义,此外还可以作“非人称代词”使用,替代作主语或者宾语的不定式、动名词或者名词性从句。It is very clear that the public want to know when these men can go into space.(很显然,公众想知道这些人什么时候能进入太空) We f
that在名词性从句中不充当句子成分,只起连接作用，没有意义，不能省略（在宾语从句中能省略）。
[5]宾语,从句,相关知识点可用作except宾语的6种不同从句I'm as good a cook as she is except when it comes to (making) pastry. 我做饭做得和她一样好, 就是不会做油酥馅饼。The old lady never spoke to anyone except when someone came to visit her. 老太太从来不
如：That they are good at English is known to us all.
The problem is that we don't have enough money.
what在名词性从句中充当句子成分，起连接作用，有意义，不能省略。what可以分解成定语从句中的先行词 + 关系代词+ that。理解为双重身份。
[6]关系代词,定语从句,相关知识点知识点1:定语从句在什么情况下省略关系词(关系代词和关系副词)(2) 当主句为there be结构时，在定语从句中作主语的that, which, who有时可省略。如：There’s a gentleman (who) wants to see you. 有一位先生要见您。(3) 当主句为it is, here is结构时，在定语从句中作主语的that有时可省略。如：Here
如：Do what he says. What (=The thing that) he said was true.
[7]said,what,相关知识点what is said above ...句型结构分析语法讲解：句子成分、什么句型句法，怎么用什么意思结构︰…what is said above…说明︰此句型意为“上面所说的”。 As we learn from what is said above, the tides can be very useful. 依照上面所说的，我们知道潮汐可以是非常有帮
