环管工艺装置原料丙烯中的氧含量工艺指标设计要求小于（）。
A、1PPm
B、2PPm
C、3PPm
D、4PPm
参考答案：D
—Where's the _______?
—It's next to the library. Do you want to get some money? [ ]
A. library
B. restaurant
C. bank
D. school
机理
