粘度对容积式流量计有改善其计量性能、降低误差的作用.
参考答案：对
-How about your journey to Mount Emei?
-Everything was wonderful except that our car ________ twice on the way.[ ]
A．slowed down
B．broke down
C．got down
D．put down
计算CO2中氧元素的质量分数，正确的表达式是（）。
A.A
B.B
C.C
D.D
