空分设备的局部加温或全面加温所用气体都是除去水分和CO2的干燥的（）。
A.工厂空气
B.氮气
C.污氮气
D.仪表空气
参考答案：A
— Where is Bob? I cannot find him anywhere.
— He ________ have been off long. I heard him make a call just now. [ ]
A. shouldn't
B. can't
C. mustn't
D. needn't
和玺彩画
