题目

What worried me was that the baby who ______ his mother during his birth was still in ICU. A . Loses B . lost C . has lost D . had lost 答案：D在化学学习过程中，常常要用到分类的方法。下列各组物质的分类正确的是 [     ]A．混合物：空气 粗盐 牛奶 B．盐：氯化钙 硫酸 硝酸钾 C．氧化物：MgO P2O5 KClO3 D．单质：铝 金刚石 氯化氢