现在网购越来越多地成为人们的一种消费方式,在2014年的“双11”网上促销活动中天猫和淘宝的支付交易额突破57 000 000 000元,将数字57 000 000 000用科学记数法表示为( ) A.5.7×109 B.5.7×1010 C.0.57×1011 D.57×109 答案:BThis chemical class is about the ______ of metals with oxygen and our teacher shows us how iron ______ air and water.A. react; reacts with B. react; reacts toC. reaction; reacts to D. reaction; reacts with