单项选择题
A deepwell pump is a type of（）.
A.screw pump
B.centrifugal pump
C.eductor
D.gear pump
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相关考题
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单项选择题
A definite advantage of using water as a fire extiguishing agent is its characteristic of（）.
A.alternate expansion and contraction as water in a liquid state becomes a vapor
B.absorption of smoke and gases as water is converted from a liquid to a vapor
C.rapid contraction as water is converted from a liquid to a vapor
D.rapid expansion as water absorbs heat and changes to steam -
单项选择题
A design modification of an anchor chain which prevents kinking is the（）.
A.detachable link
B.stud link
C.Kenter link
D.connection link -
单项选择题
A device fitted over the discharge opening on a relief valve consisting of one or two woven wire fabrics is called a（）.
A.flame stopper
B.flame screen
C.flame filter
D.flame restrictor
