操作条件下允许吸上真空高度为Hs，允许的最大安装高度为Hg,max，泵的入口速度为u1，Hf,0-1为吸入管路单位重量液体的阻力损失，则()。
A. Hg,max=Hs
B. Hg,max=Hs＋u12/2g
C. Hg,max=Hs－Hf,0-1
D. Hg,max=Hs－u12/2g－Hf,0-1
在测定离心泵特性曲线时下面的安装是错误的()
A. 泵进口处安真空表
B. 进口管路上安节流式流量计
C. 泵出口处安压力表
D. 出口管路上安调节阀
Napkin Etiquette is really important for us to master. Please choose all those suitable tips for using your napkin.
At informal meals, place the napkin in your lap immediately upon seating.
B. During formal occasions, before unfolding the napkin, wait for the hostess to remove her napkin from the table and unfold it in her lap.
C. Place the napkin in your lap upon seating.
D. When leaving the table temporarily, put the napkin on your chair.
E. At the meal's end, fold your napkin and place it to the left of your place setting.
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