定量泵只有改变转速才能改变流量。
参考答案:对
As a rough estimate (估计), this room is that. [ ]
A. three times the size as
B. the size three times of
C. three times as the size of
D. three times the size of
下列四个例子中,采用相同的物理研究方法的是
(1)根据电流所产生的效应认识电流; (2)研究电流时把它比作水流; (3)根据磁铁产生的作用来认识磁场; (4)利用磁感线来描述磁场. [ ]
A、(1)与(2)
B、(1)与(3)
C、(3)与(4)
D、(2)与(4)