【题目】—What do you think of the Huawei P7?
—Terrific, I would buy one if I ______ an iPhone 6 Plus last year.
A．didn’t buy
B．don’t buy
C．hadn’t bought
D．haven’t bought
在线课程【答案】A
【解析】代词it作形式主语代替真正主语，真正主语被后置。主语是从句，我的女儿每天都和手机玩很长时间（“my daughter plays with her cellphone for a long time every day”）。