环形炉()炉顶下压是为了提高炉压减少冷空气吸入。
A.加热段
B.均热段
C.预热段
D.对流区
参考答案:B
根据首字母及句意补全单词。
1. You should brush your teeth t _____ a day.
2. What's the m _____ with you, young boy?
3. I'm p ______ to take a trip to Kunming.
4. I'm so thirsty. I want s _____ to drink.
5. Could you take c _____ of my pet dog while I'm away?
不能在共聚单体脱气塔脱除的杂质是()。
A.甲醇
B.氧气
C.一氧化碳
D.二氧化碳