you are at home alone please don’t leave the door open. A. WhileB. AsC. BeforeD. How

问题补充：

you are at home alone, please don’t leave the door open.

A. While

B. As

C. Before

D. How

答案：

(答案→)A. While

B. As

C. Before

D. How

解析：考查连词。While 当什么时候，As 因为，Before 在什么之前，How 如何，怎样，句意：当你单独一个人在加的时候，请不要让门开着。所以选A。