this is kate,whose sister you met yesterday.为什么在sister后不能加whom?this is kate,whose sister whom you met yesterday.为什么不行？

this is kate,whose sister you met yesterday.为什么在sister后不能加whom?this is kate,whose sister whom you met yesterday.为什么不行？
this is kate,whose sister you met yesterday.为什么在sister后不能加whom?
this is kate,whose sister whom you met yesterday.为什么不行？

this is kate,whose sister you met yesterday.为什么在sister后不能加whom?this is kate,whose sister whom you met yesterday.为什么不行？
1 把whom带进句子看看是否合适 this is kate,whom sister you met yesterday.,这样的话定语从句中主语是什么了,既有sister还有 you,所以这样不行
2 whose是形容词性的代词,后面加名词 在这个从句中 whose sister,谁的妹妹,做met的宾语
3 翻译：这是凯特,昨天你见过他的妹妹