I _____ the prolem until he explaind it.A.understood B.did not understand C.had not understood D.

分类: 作业答案 • 2022-03-02 19:07:15

问题描述：

I _____ the prolem until he explaind it.A.understood B.did not understand C.had not understood D.
had understood

答

选B
not ……until 直到……才……
句意是：直到他解释了我才明白这个问题.