Wow!there are so many presents in the shop;I don't know_____to buy for my friend.

问题描述:

Wow!there are so many presents in the shop;I don't know_____to buy for my friend.
A,what
B,which
但是为什么

which是定语从句.
而这句句子是宾语从句,what在主句中充当宾语,在从句中也是充当宾语,实际上是BUY WHAT.