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
网友回答
B解析定语从句的用法。句中的主语含有一个定语从句，省略了关系代词that，one of the difficulties是作为定语从句中的宾语。have difficulty ( in ) doing sth.做某事有困难，句意“我们学习英语的一个困难是怎样记住新的单词和表达”，因此选B。