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
网友回答
A. Until
(答案→)B. While
C. As
D. Unless
解析：连词while的意思是“当.……的时候, 虽然”，如：While he loves his students, he is very strict with them. 虽然他爱他的学生, 可是他对他们很严格。