如果一个句子充当另一个句子的组成部分,这样的句子就叫做主从复合句。充当某一句子成分的句子叫做从句,带有从句的句子叫做主句。从句和主句之间是从属关系。从句和主句间有连接词加以连接。连接词共有七种。
一、从属连接词that、whether、if。
二、疑问代词who、whose、whom、what、which。
三、疑问副词when、where、why、how。
四、关系代词who、whom、whose、which、that。
五、关系副词when、where、why。
六、缩合连接代词who、what、that、which、whoever、whatever、whichever。
七、缩合连接副词when、where、why、how、whenever、wherever、however。
如:
Who did it is still a mystery.
He is the man who saved my son from drowning.
I want to finish the work before it gets dark.
希望我能帮助你解疑释惑。