一题英文题

to buy which是典型的汉语式英语。decide to do,就像I can't decide where to go.I don't know what's his name.你不会说：I don't know his name is
what.平时应注意培养自己的语感。很多问题读一下就会知道答案了！

很明显, 因为是有选择性的, 所以不用what 而用 which, 这样就淘汰掉A和C,剩下B和D,which 是一个引导词, 后面必须带有名词或词组, 如果B换成to buy which kind of MP4,那这个答案也是正确的，所以最后答案是D.
D,which to buy是定语从句,正好符合这句子,用法也正确。

i really don't know how to answer your question.
i really really don't know what to say.

选D啊 B语法上不对 不过外国人口语上有这么说的 C嘛 前面已经确定MP4了 所以不能用WHAT了

D是固定用法，TO BY WHICH 是中式英语 当然不合语法，（which,what how why 用法都一样）举个简单例子--I did't know what he was thinking.

Deside+宾语,宾语要倒装所以to buy what 不选.what to buy 表示买什么,which to buy表示买哪个.所以选d.希望能帮到你!