问题补充:
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
答案:
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。