---I’m sorry! I would have taken him to hospital if I had known he was seriously ill.B

问题补充：

---I’m sorry! I would have taken him to hospital if I had known he was seriously ill.

--- But .

A. you didn

B. you hadn

C. he wasn

D. you aren

答案：

(答案→)A. you didn

B. you hadn

C. he wasn

D. you aren

解析：

试题分析:考查动词时态。从上句的虚拟语气可知说话人是对过去已经发生事情的后悔遗憾，所以回答应该是针对过去的事实。句意：---真对不起！如果我知道他病得严重的话我就带他去医院了。---可是你没有。故A选项正确。