How can school ban mobile phones pletely some of the parents simply don’t follow the rule?
A. unless
B. when
C. until
D. before
网友回答
A. unless
(答案→)B. when
C. until
D. before
解析:句意:当一些家长不遵守规则的时候,学校怎么能完全禁止手机呢?when 表示“当…时候”,unless 表示除非,until表示直到…,before表示在…之前,故选