How did you know_____?A to buy what B to buy where C what to buy D where to buy 哪一个答案是对的,多谢.

问题描述:

How did you know_____?A to buy what B to buy where C what to buy D where to buy 哪一个答案是对的,多谢.

选C
wh-词+不定式是固定句式,所以AB不对
D缺宾语,应为where to buy it