Thank you very much indeed.If it had not been for your advice I really what I should have done.

题目

Thank you very much indeed.If it had not been for your advice I really what I should have done.
A.don’t know B.didn’t know C.hadn’t known D.wouldn’t have known

答案

选A；
句意是：真的是太感谢你了.要不是因为你给我提的建议,我真不知道自己做出了什么蠢事来.
虽然句中的 if it had not been for your advice 和 what I should have done 均用了虚拟语气（均表示与过去事实相反的假设）,但句中的“我不知道”不能用虚拟语气,因为它在陈述现在的事实.
换句话说,“我不知道”是与事实相反的假设吗?显然不是.所以它不能用虚拟语气,应用陈述语气(I don’t know),表明这是事实（表达自己对对方的感谢之意）.