题目

She was surprised to find the fridge empty; the child _____ everything! A. had been eating    B. had eaten       C. have eaten       D. have been eating   答案：B20．下列有关说法中，正确的是（　　）A．生铁、不锈钢、青铜都属于合金B．14C可用于文物年代的鉴定，14C与12C互为同素异形体C．食醋、纯碱、食盐分别属于酸、碱、盐D．糖类、油脂和蛋白质都是天然高分子化合物