A.increased；decreased
B.decreased；increased
C.decreased；decreased
D.increased；increased
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A.kg
B.MPa
C.mH20
D.None of the above
Which of the following are components of a mechanical seal? （）
(1) stationary ring
(2) rotational ring
(3) packing
(4)spring
A.(1), (2) and (3)
B.(1), (2) and (4)
C.(2), (3) and (4)
D.None of the above
A.variable stroke pumps
B.multistage pumps
C.positive displacement pumps
D.triple-ported pumps
A.mixed-flow pump
B.axial-flow pump
C.centrifugal pump
D.displacement pump
A.on top cover
B.on sides of bowl
C.in drain line on the discs
D.on the discs
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