1.Sarah had her purse stolen the day before yesterday when she was knocking about in a park, ________？
A. wasn't she B. hasn't she
C. hadn't she D. didn't she
答案与解析：D 主句是Sarah had her purse stolen the day before yesterday，表示的是发生在过去的事，故反意疑问部分应用didn't she?
2．Little ________ about H1N1 so far, so there is no doubt that many people are afraid when talking about the disease.
A. did scientists know B. scientists have known
C. have scientists known D. had scientists known
答案与解析：C 根据关键词so far，可以确定用现在完成时，故排除A、D两项；little表示否定，放句首要倒装，故答案为C项。
