whom和who应该怎么区分呢？

一个是主格，一个是宾格
做主语的时候用who
做宾语的时候用whom，很简单

选D,who 还是 whom 就看它是后面从句的主语还是宾语,在这到题里是宾语因此用whom

I have always been honest and straightforward ,and it doesn't matter______ I'm talking to.
B.who it is
who 主语/表语
whom 宾语
it doesn't matter who it is (I'm talking to. )定语从句。
= it doesn't matter it is who (that)I'm talking to.
括号内是关系代词 ，在定雨从句中作宾语， 可省略。

B.who it is

who 主语/表语
whom 宾语
it doesn't matter who it is (I'm talking to. )定语从句。
= it doesn't matter it is who (that)I'm talking to.

D,whom 宾语,I am talking to whom...,所以it is whom i am talking to.
B,在这里不行啦.听我的没错.