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單項(xiàng)選擇題

As to the piston cooling, of the following, which statement is not true?()

A.Because the piston is exposed to very high temperature, it must be cooled
B.The lower the piston cooling temperature is, the better it is
C.Both water and lube oil can be used as coolant
D.One of the piston cooling methods is vibration cooling, with better effect

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