题目

—How much are these apples? —                         ． A．Five yuan a kilo．                                      B．They are dear C．They are red．                                       D．They are big． 答案：A有关金属腐蚀与防护的叙述中正确的是（　　） A、黄铜（铜锌合金）制作的铜锣不易产生铜绿B、镀锡铁制品和镀锌铁制品的镀层破损时，镀锡层的铁更耐腐蚀C、在闸门上连接锌块保护闸门不受腐蚀是采用了牺牲阳极保护法D、银奖牌与硫磺混在一起会变黑是电化学腐蚀所致