Question

that，what在定语从句，宾语从句，名词性从句中作用

that 在名词性从句中是不是不做成分 那为什么同位语从句要用that？
that在宾语从句中做成分吗？what呢？

请举例子说明一下什么叫定语从句，什么叫宾语从句？

Answer 1

that在名词性从句中无成分无意义。
what在名词性从句中一般担当主语宾语表语的成分。
例：I know that you are right. 宾语从句that无成分
I don't know what I should do. 宾语从句what在从句中做do的宾语
宾语从句上面举过例子了，举一个定语从句：I live in the house that my parents built in 1980. that指代先行词house, that在从句中做built的宾语。

Answer 2

定语从句
定语从句所修饰的先行词可以是名词或代词，也可以是一个句子。定语从句通常位于先行词之后，由关系代词或关系副词引导。
限制性定语从句修饰先行词，对先行词起修饰作用，紧接先行词之后，无逗号，若省去，原句意思不完整。引导定语从句的关系代词有who,whom,whose,which,that等。who,whom,whose用于指人，whose有时也可指物，相当于of which；which用于指物；that既可指人也可指物，但只用于限制性定语从句中。关系代词除了引导定语从句，替代先行词外，还在从句中担任主语、宾语、定语等。
The computers and cables which make up the Internet are owned by people and organizations.

Those who live alone or who are sick may have trouble in getting close to other people.

The girl whose parents died in an accident is living with her grandmother.
宾语从句
1）宾语从句可位于及物动词、介词和某些形容词后。连词that常可省略。介词后一般接疑问词引导的宾语从句。in that(因为),except that(除了),but that(只是）已构成固定搭配，其他介词后一般不接that引导的宾语从句。
*I promised that I would change the situation.
*All this is different from what American young people would say about friendship.
*He is certain that watching so much television is not good for children.
*This article is well-written except that it is a bit too long.

2)宾语从句后如有宾补，要用形式宾语it来代替，而把宾语从句移至宾补之后。
He has made it clear that he would not change his mind.

3)在think,believe,suppose,expect等动词后的宾语从句中，如果谓语是否定的，一般将否定词移至主句谓语上，宾语从句则变成肯定形式。
He didn't think that the money was well spent.

Answer 3

首先我们要对句法有所了解。一个英语句子跟一个语文句子的语法结构基本相似，主要有主谓宾定状补（或者主系表）。从句时一个句子的附属成分，作用来说跟一个词的作用一样的；也就是说，一个从句在整个句子中充当什么成分就是什么从句：
I like the apple which is red.此句中，根据中文翻译，可以知道which is red 在整个句子中充当APPLE的定语，故为定语从句。
What I like most is the red apple.此句中，What I like most 在整个句子中作主语，故为主语从句。
Tell me what you like most.此句中，what you like most在整个句子中做宾语，故为宾语从句。
What I want to know is what you like most.此句中，What I want to know主语从句，what you like most在整句话中做IS后的表语，故为表语从句。
Everyone knows the fact that the earth running around the sun.此处that the earth running around the sun解释说明FACT，故为同位语从句。
其他可以类推。
只要记住，WHAT 不引导定语从句，并且在名词性从句中一定充当从句；THAT 在名词性从句中不充当成分。

Answer 4

不做