Doors are generally formed in the （） of the both in-line and Vee engines to give maintenance access to the crankshaft main and connecting rod large end bearing.

Dirty oil must be （） before being used again.

A.mixed with clean oil
B.purified
C.heated
D.strained

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Dirt in the fuel oil system of a diesel engine can cause （）.

A.clogged filters
B.poor combustion
C.overloading of the diesel
D.shock of fuel lines

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