题干

要鉴别己烯中是否混有少量甲苯,正确的实验方法是(  )

A:先加足量的酸性高锰酸钾溶液,然后再加入溴水

B:先加足量溴水,然后再加入酸性高锰酸钾溶液

C:点燃这种液体,然后再观察火焰的颜色

D:加入浓硫酸与浓硝酸后加热

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答案(点此获取答案解析)

B

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    Once, in a small village, lived a family with eight children. Two of the children loved 1 very much, but the family was so poor that it was impossible to send 2 of them to study at the art college at the same time. After many discussions, the two boys finally 3 a plan. They would toss(抛) a coin. The loser would go 4into the mines (煤矿) and, with his earnings(赚得的钱), 5 his brother studying at the college. Then, when the brother who won the toss finished his studies, after four years, he would support the other brother studying at the 6.

    James won the toss and Jack went down into the mines. James worked with all his heart and his paintings were much 7 than those of most of his teachers, and by the time he 8, he was beginning to make a lot of money for his paintings.

    9 James returned, the family held a big dinner for his great success. Soon after the meal began, James 10 up from his seat to drink a toast (举杯祝酒) to his dear 11 He said, "Jack, now you can go to the art college and your 12 will come true. I will take care of you. "

    But Jack said 13, "Brother, the four years in the mines has done too much to my hands, so it's too 14 Now I can' t even hold a glass. "

    To show his great love and respect, James drew his brother' s hands with 15 towards the sky.

    He called his drawing "The Praying Hands", which became very famous years later.