（） device is provided to prevent starting air from being admitted to the cylinder before the reversing is completed.

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

A.Doors
B.Aspirate gauzer
C.Coupling
D.Blind

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（） are commonly used in mechanical-hydraulic governor（调速器） to sense engine speeds.

A.Bulbs
B.Bulks
C.Flyweights
D.Flywheels

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