---Mr Wang, I have trouble the text.
---I’m sure you can, but remember it at least three times.
A. to understand; reading
B. understanding; reading
C. to understand; to read
D. understanding; to read
网友回答
A. to understand; reading
B. understanding; reading
C. to understand; to read
(答案→)D. understanding; to read
解析：have trouble doing sth表示做某事有难度或困难；remember to do sth表示记着去做某事。