就是在句中作同位语的从句。它通常有放在thought, idea, news, word(=news), plan, doubt, question, fact, suggestion, belief等抽象名词的后面,说明这些词的具体内容或含义。
同位语从句大多由that引导,也可由whether, how, when, where, why等引导,但不能由which引导。
The idea that the earth is round is not a new one. “地球是圆的”这种观点并不新鲜。
He must answer the question whether he agrees to it or not. 他必须回答他是否同意此事这们一问题。
I have no idea when he will set out. 我不知他什么时候出发。
注:有时,同位语从句并不紧跟在它所说明的词的后面。如:
The whole truth came out at last that he was a wolf in sheep’s clothing. 真相终于大白了,他原来是一只披羊皮的狼。