we admit that there are still some problems about NMET we don’t mean that it is of no use.

问题补充：

we admit that there are still some problems about NMET,we don’t mean that it is of no use.

A. Until

B. While

C. As

D. Unless

答案：

A. Until

(答案→)B. While

C. As

D. Unless

解析：考查连词。while引导让步状语从句，意思是“尽管”。