离心泵安装在特定管路系统中,已知泵的性能:Q=0.02m3/s,H=20m;管路性能:Q=0.02m3/s,H=16m。则调节阀门的压头损失为____m,其消耗的理论功率为____W。(保留一位小数)
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若被输送的流体粘度增高,则离心泵的压头____,流量____,效率____,轴功率____。(填“减小”或“增大”)
Agroup of species that coexist in a space and time and interact with one another directly or indirectly is called ( )
Places where many species reach the edges of their distributions is called ( )
A species that has a disproportionate不成比例impact on the community relative to its abundance is called ( )