疑问代词在引起从句时，称为连接代词，包括who,whom, whose, what, which, whoever, whomever, whichever, whatever，一共九个，即除了whose后不能加“-ever”后缀，其余都行。连接代词起连词的作用，主要引导名词性从句（包括主语从句、宾语从句、表语从句和同位语从句）。其中，whatever, whoever, whomever还可以引导状语从句。连接代词引导从句时，后边都用陈述语序，不用疑问语序。
连接代词在句子中作不同成分。
- 主语从句
- What he says sounds reasonable. (他说的话听起来有道理。)
- Whoever wants to go can come with me. (谁想去我就带谁去。)
- 宾语从句
- I don’t know who he is. (我不知道他是谁。)
- The man whom I met yesterday was very kind. (我昨天遇到的那个人非常友好。)
- 表语从句
- The question is who we should trust. (问题是我们该信任谁。)
- What I want to know is which road we should take.我想知道的是我们应走哪条路。
- 同位语从句
- The news that the company is bankrupt shocked everyone. (公司破产的消息震惊了所有人。)
- The idea that we should work together is a good one. (我们应该合作的想法是好的。)
- 状语从句
- Wherever you go, whatever you do, I will be right here waiting for you.无论你去哪里，无论你做了什么，我都会在这里等你。
- Whoever you are, you can’t enter this building. 不管你是谁，你都不能进入这栋楼。