名词性从句的引导词有baithat、what、which、who、whoever、whom、whomever、if等。引导名词性从句的连接词可分为三类：
一、连词（5个）
that 本身无意义。引导单一的宾语从句时that常可省略，但引导主语从句、表语从句、同位语从句时that通常不被省略
whether,if 均表示“是否”表明从句内容的不确定性
as if , as though均表示“好像”,“似乎”
以上在从句中均不充当任何成分
二、连接代词（10个）
what/whatever, who/whoever, whom/whomever, whose/whosever, which/whichever
三、连接副词（8个）
when/whenever, where/wherever, how/however, why,because
四、不可省略的连词
1.介词后的连词。
2.引导主语从句和同位语从句的连词不可省略。That she was chosen made us very happy.We heard the news that our team had won.
3.在从句中做成分的连词.
