从句一般指的是复合句.
句子的组成部分,包括主语、谓语、宾语、定语、补语、状语、表语七种
先说定语和宾语吧.
定语就是修饰主语,宾语等成分的词语也可以是句子,那就是定语从句.定语用于描述名词,代词,短语或从句的性质,特征范围等情况的词叫做定语,定语可以由名词,形容词和起名词和形容词作用的词,短语担任.如果定语是单个词,定语放在被修饰词的前面,如果是词组,定语放在被修饰词的后面.
比如说蓝蓝的天.蓝蓝的就是定语.
He is the good man.good就是定语修饰man
he is the man who helped the teacher.who helped the teacher.就是定语从句
宾语一般是介词或者动词后面的词语,句子就是宾语从句.宾语是动作的对象或承受者,常位于及物动词或介词后面.宾语可由名词、代词、数词、名词化的形容词、不定式、动名词、宾语从句等来担任.
比如他是学生.学生就是宾语.
he is a student.a student就是宾语
He said that he would go to Shanghai.that he would go to Shanghai.
就是宾语从句
从句分为三大类：定语从句,名词性从句,状语从句
第一：定语从句是指有先行词的从句
引导词为that which who whom where when as等
根据先行词在从句中充当的成分不同选择引导词
例句：做宾语we often think of the days____we spent together on the island.
A when
B which
C in which
D during which
选B the days在从句中做宾语 用which
做状语He has left Beijing,____a meeting is to be held.
A when
B where
C as
D which
选B
Beijing 在从句中做地点状语 原句为He has left Beijing.In beijing a meeting is to be held.
做主语His father died last year,____made it impossible for him to go abroad.
A when
B which
C as
D that
选B 从句中made缺少主语,这是非限制性定语从句不能that 所以选which
注意：定语从句中不能用what引导从句
that引导的定语从句充当主语 宾语 表语成分
但是对于非限制性定语从句中,一般是跟在逗号后面的从句不能用that引导
可以选择as which who whom whose 等
第二：名词性从句包括主语从句,表语从句,宾语从句,同位语从句
that在从句中不充当任何成分,也就是说用that引导的主语从句本身是完整的
what在从句中充当主语 宾语 表语成分
（一）主语从句在整个句子中作主语.
that不同于其它的连词,它不充当句子的成分,只是单纯的连接词,通常不可以省略.分句置于句首时,that绝对不可以省略.
That the driver could not control his war was obvious.
（二）表语从句：表语从句出现在系动词后,充当表语.
The trouble is that we are short of money.
（三）宾语从句：及物动词,形容词和介词后加宾语从句作其宾语.
宾语从句时态与主句相呼应,但宾语从句表示的是客观真理或普遍现象除外The teacher told us that the earth moves around the sun.
（四）同位语从句,在句中作某些名词的同位语,对前面的名词进一步说明.用在下列名词 fact,news,idea,hope,believe,hope,thought,doubt.truth,order,suggestion,word
例句：There is no doubt that he will come.
There is doubt whether he will come.
There is no possibility that….
同位语从句与定语从句容易混淆：
that引导的同位语从句与定语从句的区别：在同位语从句中：that不可以省略,不作成分;定语从句的关系代词that在定语从句作成分,作宾语时可以省略
本人的理解.嗯.有什么跟从句有关的内容可以问我的.
