问题补充:
One of the difficulties we have English is how to remember new words and expressions.
A. to learn
B. in learning
C. learn
D. learned
答案:
A. to learn
(答案→)B. in learning
C. learn
D. learned
解析:原句意思是:我们学英语时的一个困难是如何记住单词和短语.have difficulty in doing something的意思是“做某事有困难”。根据句意,可知选B.