I have had great trouble

网友回答

bhave trouble doing sth
have trouble with sth
做某事有困难
======以下答案可供参考======
供参考答案1:
B.understanding
have trouble doing sth
句型，做某事有困难 祝你进步供参考答案2:
A have trouble (in) doing sth 做...事有麻烦
供参考答案3:
B。。to后面一定要是understand..（基本词）
had 了可以直接放词-ing..