赖世雄教你学英语语法
关系词
1-9：that可做关系代词
that亦可当做关系代词，取代who,whom或which，但使用时有两个条件：
1.that之前不准有逗点，换言之，that仅出现在限定修饰的形容词从句中；
2.that之前亦不可有介词。
例：i like the girl who is sitting there.(o)
（我喜欢坐在那里的女孩。）
i like the pretty girl,that cames here every monday.(×)
i like the pretty girl,who comes here every monday.(o)
（我喜欢那个漂亮女孩，她每星期一来这里。）
he is a man whom we all respect.(o)
（他是个我们都尊敬的人。）
this is the knife with which hc killed mary.(0)
this is the knife with that he killed mary.(×)
但: this is the knife which he killed mary with(o)
（他就是用这把刀杀了玛丽。）