要证明水煤气中含有H2、CO、水蒸气，将气体通过下列试剂的先后顺序，正确的是
①无水硫酸铜 ②澄清石灰水 ③灼热的氧化铜（假设每步均反应完全）
A．①③②
B．③①②
C．①③①②
D．①③②①
答案：C
题目分析：无水硫酸铜遇水变蓝，先用无水硫酸铜检验水的存在，在利用氢气与一氧化碳的还原性通过还原产物检验氢气和一氧化碳的存在，故顺序是①无水硫酸铜、③灼热的氧化铜、①无水硫酸铜、②澄清石灰水。由于澄清石灰水中含有水，故一定要先检验氢气还原的产物水。
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| I should say I owe my success to my mother. My belief began when I was just a kid. I 1 becoming a doctor. My mother was a servant. Through her work, she found that 2 people spent a lot more time reading than they 3 watching television. She told my brother and me to watch only two to three preselected TV programs during the week. In our free time, we had to read two books from the Detroit Public Library and 4 wntten book reports to her. She would mark them up with check marks and highlights. Years later we realized her marks were a trick because my mother was uneducated. When I entered high school, I was an A-student, but not for 5 . I wanted the brightly coloured clothes and I wanted to hang out with the guys.I went fromL being an A-student to a B-student to a C-student. One night my mother came home after 6 her various jobs and I complained about not having enough Italian knit shirts. She said, "Okay, I'll give you all the money I 7 this week by scrubbing floors and cleaning bathrooms, and you can buy the family food and pay the bills. With everything paid off, you can have all the Italian knit shirts you want."I was very 8 with that arrangement but once I got through allocating (分配) money, there was 9 left. I realized my mother was a great woman to be able to keep a roof over our heads and any kind of food on the table, let alone buy clothes. I also realized that immediate satisfaction wasn't going to get me anywhere. Success required intellectual preparation. I went back to my 10 and became an A-student again, and at last I 11 my dream and I became a doctor. My mother is a woman with 12 formal education or property who used her position as a parent to change the lives of her children. There is no job more important than parenting. | ||||
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