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
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相关考题
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单项选择题
A device used to enlarge the size of an existing bore hole, having teeth arranged on its outside circumference to cut the formation as it rotates is a (n)（）.
A.enlarge bit
B.casing bit
C.hole opener
D.casing opener -
单项选择题
A Doppler log in the bottom return mode indicates the（）.
A.velocity of the current
B.bottom characteristics
C.depth of the water
D.speed over the ground -
单项选择题
A Doppler log in the volume reverberation mode indicates（）.
A.speed being made good
B.speed through the water
C.the set of the current
D.the depth of the water
