（）流量计不受被测介质的温度、粘度、密度、压力等物理参数变化的影响
A、涡轮
B、孔板
C、刮板
D、电磁
参考答案：D
微分方程y"+2y’-15y=0的通解是______。
How many ____ are there and _____ milk is there in the bottle?
A．water how many
B．cup of water how much
C．cups of water how much
D．cups of water how many
