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單項(xiàng)選擇題

Since the burning or combustion takes place within the engine itself, the engine is known as （）.

A.a fire -tube boiler
B.an internal combustion engine
C.an external combustion engine
D.an internal combustion generator

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單項(xiàng)選擇題

Shims of different thicknesses are inserted between the shells to enable adjustment of （）.

A.the bearing clearances
B.the bearing thickness
C.the bearing strength
D.the bridge hardness

單項(xiàng)選擇題

Sediment collects in a tubular purifier （）.

A.on top cover
B.on sides of bowl
C.in drain line on the discs
D.on the discs