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單項(xiàng)選擇題

The pressure difference before and after the lube oil filter indicates （）the filter should be cleaned.

A.when
B.how
C.where
D.whether

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單項(xiàng)選擇題

A diesel engine which is rated for normal operation at a crankshaft speed of 800 RPM, is commonly classed as a （）.

A.slow-speed diesel
B.medium-speed diesel
C.high-speed diesel
D.constant-speed diesel

單項(xiàng)選擇題

The three basic parts of any eductor are the nozzle, the suction chamber, and the （）.

A.injector
B.compressor
C.diffuser
D.siphon