If I had known that, I     （）    so.

题目解析[填写题目解析]： 题目：If I had known that, I （） so. A. wouldn’t do B. wouldn’t have done C. won’t do D. have not done 答案：B 解析：这是一个虚拟条件句，表示与过去事实相反的情况。"If I had known that"表明这个动作发生在过去，而且是与过去事实相反的情况。在虚拟条件句中，主句的动作要用"would have + 过去分词"的形式。正确的答案是B，"wouldn't have done"表示"本来不会这样做"。