题目

— Excuse me. Will you please tell me the way to the railway station?— Oh, sorry, but I don't know. You go and ask the policeman over there. A . may B . must C . should 答案：C在北方的冬季，常见的几种物态变化现象中，属于凝华的是（　　）A．室外冻冰的衣服变干B．房间窗户玻璃的内表面出现冰花C．湖面结了厚厚的一层冰D．正在跑步的人，口中呼出“白气”