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單項(xiàng)選擇題

The four-stroke cycle begins with the piston （）.

A.coming up from the BDC
B.coming up from the TDC
C.coming down from the BDC
D.coming down from the TDC

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單項(xiàng)選擇題

Pump up the starting air reservoirs to their maximum pressure and （）the air reservoirs and air system.

A.open
B.close
C.drain
D.vent

單項(xiàng)選擇題

James Watt （）the steam engine in 1796.

A.discovered
B.had discovered
C.invented
D.had invented

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