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單項選擇題

（） are formed by abrasive particles entering the bearing and scoring the shaft.

A.Grooves
B.Recesses
C.Ridges
D.Nips

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單項選擇題

（） are fitted in the exhaust system and facilitate charge removal and scavenging in each cylinder.

A.Diffusers
B.Compressors
C.Steam boilers
D.Soot blowers

單項選擇題

（） provide the water to the pistons.

A.Pneumatic pipes
B.Hydraulic pipes
C.Telescopic pipes
D.Operating gas pipes