要从高锰酸钾加热完全分解后的剩余物中回收二氧化锰固体，有下列操作可选择：
①过滤；②烘干；③加水溶解；④水洗；⑤蒸发结晶。其操作顺序正确的是 （ ）
A．①→②→③→④
B．③→②→①→⑤
C．③→①→④→②
D．③→①→⑤→④
答案：C
高锰酸钾能分解生成锰酸钾和二氧化锰固体，其中锰酸钾易溶于水，而二氧化锰不溶于水，故可以采用过滤的方法进行，首先使固体溶于水，然后过滤，未得到较纯净的二氧化锰，需对固体进行洗涤，然后烘干即可，故其顺序为③①④②，观察选项，故选C
One night , a poor young artist stood at the gate of the subway station, _____ his violin . Some passers-by（行人） slowed down their paces and put some money into the hat of the young man. The next day the young artist came to the same place. Different from the day before, he took out a large piece of paper and _____ it on the ground and put some stones on it . Then he began playing. Before long , many people were attracted by the words on that paper which said, “ Last night a gentleman ______George Sang put an important thing into my hat by mistake. Please come to claim（认领）it soon.” A middle-aged man ran there _____ and rushed through the crowd to the violinist and grabbed （抓住）his shoulders and said, “ Yes, it is you. You did come here. I knew that you are an( a ) _____ man and would certainly come here.” The story turned out to be this: George Sang bought a lottery ticket a few days ago. The award opened yesterday and he won a prize of 5000,000 dollars. _______ his way home, he took _____ 50 dollars and put it in the violinist’s hat. However, the lottery ticket was also thrown in . The violinist was a student at an Arts College . He had booked the ticket to flight and came back to ____ he was given the lottery ticket. Later someone asked the violinist _____ he didn’t take the lottery ticket for himself. The violinist said, “ Although I don’t have much money, I live happily. _____ if I lose honesty, I won’t feel happy forever.”
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