单选题 If I ______ that your business was growing so rapidly, I wouldn't have been worried about it.
A. know B. knew
C. had known D. have known

【正确答案】 C
【答案解析】[解析] 本题考查虚拟语气的时态搭配。主句中用的是would have done，if引导的虚拟条件句中应用过去完成时。