哪些因素会影响氧气纯度?
参考答案:
1、)氧气取出量过大;
2、)液空中氧纯度过低;
3、)冷凝蒸发器液面过高;
4、)塔板效率下降;
5、)精馏工况异常;
6、)主冷泄漏;
It is ______taking the trouble ______a job fully to new employees.
A.worthy; explaining
B.worthwhile; to explain
C.worthy; to explain
D.worthwhile; explaining
EAN-13码的编码规则()。
A.唯一性
B.永久性
C.有含义
D.无含义