題目： If you had trouble _______ what is said to you, you _____ ask for a repetition politely.
2020-02-27
A. understand; could B. understanding; could
C. to understand; can D. understanding; can
正確答案：B
試題解析：
A. understand; could B. understanding; could
C. to understand; can D. understanding; can
正確答案：B
試題解析：
