1. 关系代词that与who互换的场合

　　关系代词that与who均可指人，有时可互换。如：

　　The man that [who] stole your car has been arrested. 偷你汽车的人已经捕获。

　　用当于all, everyone, everybody, no one, nobody和those后面引导定语从句时，通常用who，其实也可用that。如：

　　Everyone who [that] knew him liked him. 认得他的人都喜欢他。

　　Nobody who [that] watched the match will ever forget it. 看了这场比赛的人都不会忘记它。

　　2. 通常要用 that的场合：

　　①当先行词是一个既指人又指物的并列词组时，通常要用关系代词that。如：

　　I made a speech on the men and things that I had seen abroad. 我就我在国外所见到的人和事作了报告。

　　定语从句that I had seen abroad在句中修饰the men and things，故只能用that来引导;如果用who来引导，显然与被修饰的things不匹配。

　　②当先行词是who时(为避免重复)，通常要用关系代词that。如：

　　Who is the man (that) you were talking to? 刚才和你讲话的人是谁?

　　③当关系代词在定语从句中作表语时(可省略)，通常要用关系代词that。如：

　　Tom is not the boy (that) he was. 汤姆这孩子已不是以前那个样子了。