一、缺成分用代词性连接：词.what,whatever,who,whoever,which,whichever,whom,whomever.
二、不缺成分用代词性连接词：when,whenever,where,wherever,that,however,how.
具体需要哪个看情况。
扩展资料：
名词性从句是英语三大从句之一。包括四个分支：主语从句、宾语从句、表语从句和同位语从句。既然是复合句，也就是由两者或两者以上的句子复合而成。两句话合二为一的时候需要一个连接词。
最常见的连接词是that在宾语从句中的运用，如：I know that you will come. 句中的that 就是连接词，作用就是连接主句和从句，不充当成分也没有含义，只起风向标的作用，告诉你接下来的部分是一个整体，及that you will come 充当know 的宾语。
whether和if 也是引导名词性从句的连词，与that相同的地方是也不充当从句中的成分，但是是有含义的，“是否”。通常用于有疑问的句子，确定性。我们把that,whether, 和if 称为名词性从句连接词里的“3”。
名词性从句连接词里的“4”：where, when, why, how。此时从句中主谓宾这种主要成分都是不缺少的，缺少的是状语部分，如：I want to go to Walmart, but I don’t know_____ it is. 此时填where，缺少地点。
名词性从句连接词里的“5”：what,who, whom, which, whose. 缺成分指物用what；缺成分指人用who。
如：______ doesn’t does kill you makes you stronger. 填what 指事物。I don’tknow _____ took it away. 填who 指人。which 和 whose 后面通常还需接一个名词，如：I don’t know whichone I should buy. I don't know whosebook it is.
变体部分：whatever，however等相当于no matter what，no matterhow，如：I will do _____ makes her happy. 填whatever。
缺成分，用连接代词what，whatever, which, whichever,who, whoever,whom,whose等，
不缺成分用that，whether,
其实，连接副词when ,where,how,why等在其引导的名词性从句中作状语，也算做了成分
不缺成分用代词性连接词，when,whenever,where,wherever,that,however,how.
具体需要哪个看情况。本回答被提问者和网友采纳
一、不缺成分时：
当从句有疑问意义时，用从属连接词whether和if。
I don't know if it's right for her.
I don't know if I can get a good job in Los Angeles.
I wonder if a move would be a bad thing for her.
He asked me if I wanted the job.
当从句没有疑问意义时，用从属连接词that。
That they were in truth sisters was clear from the facial resemblance between them. 很明显，她们确是亲姐妹，她们的脸型很相似。
二、缺成分时：
当从句缺成分，用疑问代词、疑问副词、缩合连接代词和缩合连接副词来引导。
I wonder what the problem is.
I don't know where they are.
I don't understand why they didn't come.
We'd like to know what the young people want.
We'd like to hear what Robbie thinks about it.
We don't know where he went.
Whoever comes is welcome. 不论谁来都欢迎。(关联词是缩合连接代词whoever)
Wherever you are is my home—my only home. 你所在的任何地方都是我的家——我惟一的家。(关联词是缩合连接副词wherever)