单项选择题
It is very necessary that each cylinder （） before the charged air is compressed.
A.is scavenged
B.has been scavenged
C.be scavenged
D.was scavenged
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相关考题
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单项选择题
It is very necessary that each cylinder （） before the charged air is compressed.
A.is scavenged
B.is atomized with fuel oil
C.be scavenged
D.be atomized with fuel oil -
单项选择题
It is very important that each cylinder should be （） scavenged before the charged air is compressed.
A.well
B.good
C.excellent
D.respectively -
单项选择题
It is necessary to remove （） from the cooling water spaces to improve heat transfer.
A.lime
B.frost
C.scale
D.scar
