高等继续教育 / 大学英语I
正确率：100%
题型描述: 单选题
The students didn’t manage to work out the problem _ _ _ _ their teacher had explained how.
A. as
B. when
C. unless
D. until
The students didn’t manage to work out the problem _ _ _ _ their teacher had explained how.
A. as
B. when
C. unless
D. until
参考答案：
佳题速递：