单选题 ______ you were busy, I wouldn't have bothered you with my questions.
A. If I realized B. had I realized
C. Did I have realized that D. As I realized

【正确答案】 B
【答案解析】本题测试虚拟语气的一种倒装结构，由if引导的虚拟语气中，若从句中有were，had，could，should，可省去if句子倒装。
译文：如果我意识到你很忙，我就不会麻烦你来问你问题了。