◎ 题干
The school rules state that no child shall be allowed out of the school during the day, _____ accompanied by an adult.

A. once
B. when
C. if
D. unless
◎ 答案
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“The school rules state that no child shall be allowed out of the school during the day, _____ accompanied by an adult. [ ]A. once B. when C. if D. unless …”主要考查了你对  【从属连词】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。