题目

What does the boy’s father look like? A.He has short brown hair. B.He has small eyes. C.He has short black hair. 答案：【答案】C【解析】W: Is that man with short black hair your uncle?M: No, he is my father.下列化学概念之间存在绝对界限的是A. 混合物和纯净物B. 有机物和无机物C. 浓溶液和稀溶液D. 被氧化和被还原