什么叫离心泵的特性曲线？
参考答案：
离心泵的流量Q、扬程H、轴功率N及效率η之间的关系曲线，叫离心泵的性能曲线。
—Why were you shouting?
—Alice asked me to speak more . The line was bad.
A. quietly B. politely C. loudly
下列化合物属于双环单萜的是
A．薄荷醇
B．薄荷酮
C．冰片
D．梓醇
E．莪术醇
