在离心泵出口处安装调节阀，改变阀门开度，使管道阻力变化，从而会损耗一部分功率。
参考答案：对
— Are you going to the picnic with us tonight?
— Yes.
— You won't be late, _____? [ ]
A. should you
B. will you
C. don't you
D. can you
所有的三维模型都可以查询体积信息。（）
