采集零空气样品所使用的活性炭吸附管临用前在（）二保护下400℃烘（）h；冷却至室温，装入双球玻璃管中，两端用玻璃棉塞好，密封保存。
参考答案：氮气；2
在负荷不变情况下，造成精馏塔回流温度升高的可能原因包括（）等。
A、塔釜加热量大
B、冷凝器换热效果差
C、冷剂量小
D、冷剂供给温度升高
1. Mr. Sun can speak English very well, ________?
2. Let's finish the work as soon as possible, ________?
3. There won't be a football match tonight, ________?
4. He did little work, _______?
5. She usually has breakfast at 7 o'clock, ________?
6. Everybody saw him, ________?
7. I don't think she is good at dancing, _________?
