English speakers prefer to have prolonged ______ contact while conversing.
参考答案:eye
乙烯装置工艺空气的压力通常为()。
A.<0.4MPa
B.<0.5MPa
C.>0.5MPa
D.>0.7MPa
计算题:(A-A-014)已知某一侧线油品流速为10m/s,管线用φ219×8的钢管,求油品的流量?