单项选择题
The most important factor that causes the wear of the engine parts is （）.
A.excessive heat
B.friction
C.oxidation
D.high pressure
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相关考题
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单项选择题
In the closed cooling system, the water （）.
A.is made to circulate out of the system
B.is made to circulate within the system
C.is made circulate within the system
D.is made circulate out of the system -
单项选择题
If the temperature drops low enough, oil will not flow, （） just tell us the temperature.
A.Hash point
B.Viscosity
C.Pour point
D.Cetane number -
单项选择题
The （） can tell us how much heat we can get from the burning of an oil.
A.viscosity
B.flash point
C.cetane number
D.calorific value
