I found I could easily make myself by using sign language. A. understoodB. understandC.

问题补充：

I found I could easily make myself by using sign language.

A. understood

B. understand

C. to understand

D. being understood

答案：

(答案→)A. understood

B. understand

C. to understand

D. being understood

解析：

这题考查过去分词做宾语补足语的用法，myself和understand是被动的关系。make sb done“使…被…”，根据句意：我发现用手势语很容易使自己被理解。选A。