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單項選擇題The load on the crosshead pin is always （）, so it is the （）half of the bearing which is subject to wear.

A.upwards；top
B.upwards；bottom
C.downwards；top
D.downwards；bottom

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1.單項選擇題Because the top of the connecting rod swings about the pin and changes direction each time the piston reaches mid-stroke, the relative speed between bearing and pin at mid-stroke is zero, （）to a maximum as the piston approaches top or bottom dead center and then （） back to zero again as the piston approaches mid-stroke and the connecting rod changes direction.

A.accelerates；decelerates
B.accelerates；accelerates
C.decelerates；decelerates
D.decelerates；accelerates

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2.單項選擇題The slippers run （） in the crosshead guides as the piston and rod are （）and prevent the top of the connecting rod from moving sideways.

A.up and down；reciprocating
B.up and down；rotating
C.back and forth；reciprocating
D.back and forth；rotating

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3.單項選擇題The connecting rob is fitted between the crosshead and the crankshaftIt transmits the firing force, and together with the crankshaft convert the （） motion to a （） motion.

A.rotary；reciprocating
B.up and down；fore and aft
C.fore and aft；up and down
D.up and down；rotary

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4.單項選擇題The （） of the semi-built method of the construction crankshaft is that by making the two webs and crankpin from a single forging the grain flow in the steel follows the web round into the crankpin and back down the other web.

A.advantages
B.disadvantages
C.power advantages
D.power disadvantages

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5.單項選擇題Today, crankshafts for large 2-stroke crosshead engines are of the （）type.

A.semi-built
B.built-up
C.solid forged
D.individual forged

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