从句
（一）名词性从句
1.名词性从句有四种：
主语从句： 句子做主语 What he said is right.
宾语从句： 句子做宾语  I think that he is honest.
表语从句： 句子做表语  My advice is that we should set out
同位语从句：句子做同位语 The news that our team won is right.
2.名词性从句的引导词：所有的疑问词及其疑问代词+ ever构成的词 ；that； if/whether。除了在宾语从句中的that 可以省略外，其他引导词都不能省略
3. ▲The city is not ___ it used to be.  A what  B that C which  D why
▲After ___ seemed a long time, it was his turn to see the doctor.
A that  B it  C what  D which
▲Perservance is a kind of quality and that’s____ it takes to do anything well.  A what  B that  C which  D why
是否填what应具备的条件：
①what引导的名词短语在整个句子是否做成分(即做主语，宾语，或表语)
②在what引导名词短语中what是否做成分(即做主语，宾语，或表语，定语)
注：what引导的名词短语一般译为：…的东西(…的人；…的地方等)
(二) 定语从句
1.什么是先行词：
在定语从句中被修饰的名词或代词是先行词。
2.关系词包括哪两种：关系代词和关系副词。
3.关系词在什么情况下可以省略：
先行词在定语从句中做宾语的时候可以省略。
4.关系词在定语从句中有什么汉语意思？
关系词在定语从句中没有汉语意思。
whether是什么意思
5.怎样把先行词放入定语从句中
(1)当是关系代词时
把先行词放在关系词后面的句子中的适当的位置(主语，宾语，或表语的位置)
Is this the photo that you took last summer?
→You took the photo last summer.
(2)当关系代词是whose时
①Whose +n.改为先行词’s +n.
②把先行词’s +n.放在后面这个句子中的适当位置。(主语，宾语，或表语的位置)
It was an island whose name I have forgotten .
→I have forgotten the island’s name.
(3)介词+关系代词时
①介词+关系代词改为介词+先行词
②把介词+先行词部分放在后面这个句子中的适当位置。
The man with whom she was traveling is her boyfriend.
→she was traveling with the man.
(4)复杂介词+关系代词时
①复杂介词+关系代词改为复杂介词+先行词
②把复杂介词+先行词部分放在后面这个句子中的适当位置。
He has five sons, 3 of whom are teachers.
→3 of five sons are teachers.
(5)当是关系副词时
把先行词放入关系副词后面这个句子中的适当位置，同时在先行词前面加适当的介词
This is the room where I lived.
→I lived in the room.
6.如何确定用关系代词还是关系副词：
①当先行词放在定语从句中要做主语，宾语，或表语时，要用关系代词(which /that/who/whom/whose)
②当先行词放在定语从句中需要加介词做状语时，要用关系副词(when/where/why)