问题
单项选择题
采用酚试剂比色法测定空气中的甲醛，对SO2的干扰采取的排除方法是
A.采样时，将气样先通过普通滤纸
B.采样时，将气样先通过硫酸锰滤纸
C.采样时，将气样先通过水溶液
D.采样时，将气样先通过碱性溶液
E.采样时，将气样先通过活性炭管
答案
参考答案：B
解析：
用酚试剂比色法测定空气中的甲醛，用硫酸锰试纸预先过滤空气样品可去除二氧化硫的干扰。
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采用酚试剂比色法测定空气中的甲醛，对SO2的干扰采取的排除方法是
A.采样时，将气样先通过普通滤纸
B.采样时，将气样先通过硫酸锰滤纸
C.采样时，将气样先通过水溶液
D.采样时，将气样先通过碱性溶液
E.采样时，将气样先通过活性炭管
参考答案：B
解析：
用酚试剂比色法测定空气中的甲醛，用硫酸锰试纸预先过滤空气样品可去除二氧化硫的干扰。
| 阅读理解。 |
| John and Laura were husband and wife. Laura had beautiful, long brown hair, shining like the silk. Every morning she combed her hair many times. John had a golden pocket watch (怀表) left by his father. He loved it very much. Christmas was coming. The couple (夫妇) both wanted to send a gift to each other. John went to the shop and found a nice comb. He thought Laura's hair would look prettier with the comb on it. But the comb was so dear that he couldn't afford it (买不起). He thought and thought. At last, he sold his pocket watch and bought the comb. When he got home, he was surprised to see Laura's short hair. Laura opened her hands. There was a golden watch chain (金表链) in her hands. "Merry Christmas!" said Laura. John said "Merry Christmas" too and passed his wife a little box with tears in his eyes. Laura opened it… |
| 1. John and Laura were _____. |
[ ] |
| A. rich B. poor C. not happy D. hungry |
| 2. How did Laura buy the golden chain? |
[ ] |
| A. She worked hard B. She borrowed some money C. She sold her long hair C. She sold their house |
| 3. Why did John sell his pocket watch? |
[ ] |
| A. Because he loved Laura B. Because it was Christmas C. Because he had little money D. All of the above |
| 4. What was in John's little box? |
[ ] |
| A. A new watch B. A new dress C. A new comb C. A turkey |
| 5. What can you learn from this story? |
[ ] |
| A. On Christmas you must give dear gifts to your friends. B. You have to get more money. C. You mustn't buy useless (没用的) things. D. A friend in need is a friend indeed. |