最常用的引导词用以引导同位语从句的最常用的连词是that。如：The news that we are having a holiday tomorrow is not true.明天放假的消息不实。The idea that you can do this work without thinking is wrong.你可以不动脑筋做此工作的想法是错误的。有时也可以用whether、连接代词或连接副词等来引导。如：It is a question how he did it.那是一个他如何做的问题。Do you have any idea where he lives?你知道他住在哪里吗?She had no idea why she thought of him suddenly.她不明白她为什么突然想到了他。We are not investigating the question whether he is trustworthy.我们不是在调查他是否可信赖的问题。同位语从句可以用if引导吗表示“是否”的whether可以引导同位语从句，但是与之同义的if不能用于引导同位语从句。如：他是否会来还不一定。误：There is some doubt if he will come.正：There is some doubt whether he will come.让我们来讨论是否该做的问题吧。正：Lets discuss the question if we should do it.正：Lets discuss the question whether we should do it.同位语从句可以用which引导吗大家知道，在定语从句中，若先行词为指事物的名词，有时既可用that来引导定语从句，也可用which来引导定语从句，但在同位语从句中，习惯上要用that，而不用which。如：我坚信他会获胜。误：I hold a firm belief which he will win.正：I hold a firm belief that he will win.我得出结论这样做是不明智的。误：Ive come to the conclusion which it was unwise to do that.正：Ive come to the conclusion that it was unwise to do that.同位语从句可以用what引导吗what不能用于引导定语从句，但可以引导同位语从句，尤其用于idea之后。如：Have you any idea what time it starts?你知道什么时候开始吗?I didnt have the faintest idea what you meant.我一点也不明白你是什么意思。Do you have any idea what it means to be poor?你知道贫穷意味着什么吗?