So difficult it to work out the problem that I decided to ask Tom for advice.
A. I did find
B. did I find
C. I have found
D. have I found
网友回答
A. I did find
(答案→)B. did I find
C. I have found
D. have I found
解析：以so＋adj./adv.开头的句子要在主句中进行部分倒装。句意：我发现这个问题是那么的难，就问了汤姆。