题目

___in the queue for half an hour, Tom suddenly realized that he had left his wallet at home. A.To wait          B.Having waited          C.Have waited               D.To have waited 答案：B物质的性质决定其用途。下列因果关系不成立的是A．洗洁精具有乳化功能，用于去除油污B．磷燃烧能产生白烟，用于制作烟幕弹C．钨的熔点高且能导电，用于制作白炽灯丝D．铁的活泼性比铝弱，铁制品比铝制品在空气中更耐腐蚀