You must reply to that boy who wrote you a letter 谁是主语能不能用whom

问题描述:

You must reply to that boy who wrote you a letter 谁是主语
能不能用whom

这个句子主干是You must reply to sb.然后宾语用的是一个定语从句,that boy是从句的主语,wrote you a letter是定语,修饰that boy.其实就是2个句子:
1.You must reply to that boy.
2.The boy wrote you a letter.
that boy是先行词,在从句里面作主语,所以用表示人的主格who

不能,定语从句中差主语,而whom只作宾语,who既可作主语也可作宾语,但介词提前时只用whom,如for whom,with whom

you
是主语.
You must reply to that boy who wrote you a letter
who wrote you a letter
分句里who 作主语,不可以换.
You must reply to that boy who/whom you wrote a letter.
这句可以,分句中作宾语

you 是主语
可以换