问题补充：
So difficult it to live in an English-speaking country that I determined to learn English. A. I have felt B. have I felt C. I did feel D. did I feel
网友答案：
热心网友 1楼
A. I have felt B. have I felt C. I did feel (答案→)D. did I feel 解析：考查倒装句。以“so + 形容词”开头的句子要用部分倒装，可排除A、C; 由 determined 可知用一般过去时。
