宾语从句：在句子中起宾语作用,如：I konw that he has returned.其中that he has returned作为宾语来用,为宾语从句. 状语从句：起副词作用,分为时间、地点、原因、条件、目的、结果、让步、方式和比较等. 定语从句：用作修饰主句的某个名词性成分,相当于形容词,又叫形容词性从句,一般紧跟在它所修饰的先行词后面,如：I konw the reason why he was so angry.如果将why he was so angry去掉,原句主句部分仍可成句. 表语从句：多接在be动词后面,用来说明主语,如：The question is how he did it.
