一、關於結構中的that
此結構中,除強調的是作主語或賓語的人時可以用who外,其它任何情況都只能用that。如:
It was Kate that/who told me about it. 是凱特告訴那件事的。
It was yesterday afternoon that she told me about it. 是昨天下午她把那件事告訴我的。(that不能用when替代)
二、關於結構中be的形式
原句中謂語動詞是過去式,強調結構的be用is,原句謂語動詞是現在時或將來時,強調結構的be用was。如:
It is he that likes playing games. 是他喜歡打遊戲。
It is tomorrow that we will have a meeting. 是明天我們要開會。
注:be有時與表示推測的.情態動詞連用。如:
It must be John that/who cleaned the room. 一定是約翰打掃房間的。
三、關於主謂一致問題
被強調的是原句的主語時,要注意that/who後的謂語動詞與原句主語一致。如:
It is I that am in trouble. 是我陷入了困境。