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單項選擇題

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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單項選擇題

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

單項選擇題

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