（） is a source of power by which the diesel engine may operate.

（） is a precaution which contributes to avoiding trouble under normal operating conditions.

A.Constant inspection
B.Keeping constant load
C.Remaining constant temperature
D.varying speed

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（） are mounted on and bolted to the bed-plate cross girders.

A.The crankshaft
B.The crankcase
C.The guide-ways
D.The frames

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