宾语从句的引导词有：
连词：that(that常可省略),whether,if；
代词：who,whose,what,which；
副词：when,where,how,why等。
一、that引导的宾语从句：
1、可跟that从句做宾语的动词有：
say, think, insist, wish, hope, demand, imagine, wonder, know, suppose, see, believe, agree, admit, deny, expect, explain, order, command, feel, dream, suggest, hear, mean, notice, prefer, request, require, propose, declare, report等。
例句：The boy believes that he will travel through space to other planets.
2、当主句谓语动词是 think, believe, suppose, expect 等词，而宾语从句的意思是否定时，常把否定转移至主句表示。
例句：I don’t think it is right for him to treat you like that.
3、在以下情况中不能省略
①当句中的动词后接多于两个由that引导的宾语从句时，第一个that可省，但后面的that不可省。
例句：He said (that) you were too young to understand the matter and that he was asked not to tell you.
②当主句的谓语动词与that宾语从句之间有插入语时，that一般不可省。
例句：Just then I noticed, for the first time, that our master was wearing his fine green coat and his black silk cap.
③当that从句是双宾语中的直接宾语时，that不可省。
例句：I can’t tell him that his mother died.
二、由whether,if 引导的宾语从句：
由whether(if)引导的宾语从句，实际上是一般疑问句演变而来的。意思是“是否”。宾语从句要用陈述句语序。一般说来，在宾语从句中whether与if可以互换使用，但在特殊情况下if与whether是不能互换的。
例句：I wonder whether(if) they will come to our party.
三、只能用whether，不能用if引导的宾语从句：
1、在带to的不定式前
例句：We decided whether to walk there.
2、在介词的后面
例句：I’m thinking of whether we should go to see the film.
3、在动词后面的宾语从句时
例句：We discussed whether we had a sports meeting next week
4、直接与or not连用时
例句：I can’t say whether or not theycan come on time.
四、只能用if不能用whether引导的宾语从句：
if引导否定概念的宾语从句时。
例句：He asked if I didn’t come to school yesterday.
五、连接代词和连接副词引导的宾语从句：
这样的宾语从句实际上是由特殊疑问句变化而来的，宾语从句要用陈述句语序。用于这种结构的动词常常是：see, say, tell, ask, answer, know, decide, show, find out, imagine, suggest, doubt, wonder, discover, understand, inform, advise等。
1、英语中的连接代词有：who,whom,whose,which,what,在句中担任主语、宾语、定语或者表语。
例句：Can you tell me whom you are waiting for?
2、英语中的连接副词有：when,where,why,how，在句中担任状语的成分。
例句：None of us knows where these new parts can be bought.