Question

---Mr. Wang, I have trouble       the text.

 --- Remember       it three times at least.

1. A.
   to understand; reading
2. B.
   understanding; reading
3. C.
   understanding;to read
4. D.
   to understanding; to read

Answer 1

C
have some trouble in doing sth，第一空用动名词，故将A的排除，根据上下文，可知后文说的是记得曾经做某事，故用动名词，故选答案为C