Question

The twin sisters look so much alike that I could never tell__

A who is who B whom is whom C what is what D which is which

Answer 1

A who is who “谁是谁”“人们的情况(姓名、工作、身份等)”
I don’t know anyone at this party; you must tell me who’s who.
这晚会上我一个人也不认识，你要告诉我哪个是哪个(即给我作介绍)。
B whom is whom 应该没有这个
C what is what 表示“哪个是哪个” “好东西与坏东西”He can’t tell what’s what. 他好丑不分
D which is which “哪个是哪个”，通常用于区分两个十分相似的人或事物

所以应该选D

Answer 2

D which is which
翻译： 这对双胞胎一模一样，我分辨不出谁是谁

These kittens look exactly alike. How can you tell which is which?
这些小猫看上去一模一样--你怎麽能分出哪个是哪个？
I can't tell which is which because they are so alike.
我分辨不出谁是谁，因为他们太像了。

Answer 3

B 分不清谁是谁 tell 的 宾语 用宾格

Answer 4

D 双胞胎姐妹长得太像了以致于我分不出哪个是哪个
前面有范围的了，所以用which