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【单选题】
Which of the listed statements is correct concerning the starting of centrifugal pumps? .A.
They should always be started with the discharge valve closed
B.
They should always be started with the discharge valve opened
C.
A priming pump is always required to flood the impeller suction
D.
They should always be started with the sealing line valves closed
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【简答题】It came as something of a surprise when Diana, Princess of Wales, made a trip t Angola in 1997, to support the Red Cross’s campaign for a total ban on all anti-personnel landmine landmines(地雷)Within h...
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【单选题】When securing a flash-type evaporator for an extended period of time, you should _____.
A.
fill the unit with saltwater
B.
fill the unit with de-scaling compound
C.
completely drain the unit
D.
tightly seal the unit to exclude air
【简答题】阅读理解。 It came as something of a surprise when Diana, Princess of Wales, made a trip to Angola in 1997, to support the Red Cross's campaign for a total ban on all anti-personnel landmines. Within hours...
【简答题】* 某一套管换热器的内管为 165mm* 4.5mm 的钢管,内管中热流体被冷却,热流体流量为 3000kg·h -1 ,比热容为 1.87kJ·kg -1 ·K -1 ,进、出口温度分别为 90 °C、 60 °C,环隙中冷却水进出口温度分别为 20 °C和 45 °C,水的比热容为 4.187kJ·kg -1 ·K -1 ,总传热系数 K 为 1600 W·m -2 ·K -1 (以外表面为基...
【单选题】It came as something of a surprise when Diana, Princess of Wales, made a trip to Angola in 1997 , to support the Red Cross's campaign for a total ban on all anti-personnel landmines (地雷) . Within hour...
A.
to voice her support for a total ban of landmines
B.
to clarify the British government's stand on landmines
C.
to investigate the sufferings of landmine victims there
D.
to establish her image as a friend of landmine victims
【单选题】It came as something of a surprise when Diana, Princess of Wales, made a trip to Angola in 1997, to support the Red Cross's campaign for a total ban on all anti-personnel landmines. Within hours of ar...
A.
to clarify the British government's stand on landmines
B.
to establish her image as a friend of landmine victims
C.
to investigate the sufferings of landmine victims there
D.
to voice her support for a total ban of landmines
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