I had a little troubleEnglish grammar.A. learnB. learnedC. learningD. to learn

问题补充：

I had a little troubleEnglish grammar.

A. learn

B. learned

C. learning

D. to learn

答案：

A. learn

B. learned

(答案→)C. learning

D. to learn

解析：表示在某方面有麻烦，通常用介词in，介词in有时可省掉，介词后用动名词，故

选C,本题的结构为have a little trouble（in） doing sth。