题目

互为同素异形体的一组物质是（     ）   A、 金刚石和石墨    B、双氧水和水    C、干冰和冰     D、氧气和液氧 答案：A_____ there ______ housework for your mum at your home? [     ]A. Are; too many B. Is; too many C. Are; too much D. Is; too much