【答案】Lisa is thinking about which book ________.

Lisa is thinking about which book ________.

A. buy B. bought C. buying D. to buy

【答案】

D

【解析】

句意：丽莎正在考虑买哪本书。疑问词加不定式的作用相当于一个宾语从句，which book to buy相当于一个宾语从句放在介词about之后作宾语。to buy是动词不定式作定语修饰book。故选D。