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
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
D
考查连词。句意为：“学校规则说明任何孩子在白天不允许出校门，除非有成人陪同。”A项意为“一旦”； B项意为“当……的时候”； C项意为“如果”； D项意为“除非”；所以，根据句意，答案为D。