She was afraid that unless the train speeded up she would lose her _____ to Scotland. A. ticket B. place C. seat D. connection 答案:D超市里,有成百上千种商品,为了便于顾客选购,住住分门别类,有序地摆放.在化学学习中,我们也要将物质进行分类.请将下列物质按要求分类.(用序号)①空气;②二氧化硫;③氧气;④硫粉;⑤高锰酸钾;⑥氮气;⑦海水;⑧冰水混合物;⑨过氧化氢溶液;⑩二氧化锰其中属于混合物的是______;属于纯净物的是______;属于化合物的是______;属于单质的是______.