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單項(xiàng)選擇題

When turning the engine with turning gear, you should keep the indicator cocks （）.

A.attached to the indicators
B.opened
C.closed
D.broken

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單項(xiàng)選擇題

When to remove scale from the cooling spaces, acid solution （） in the system can be tested from time to time by putting some on to a piece of lime.

A.strength
B.dense
C.percentage
D.velocity

單項(xiàng)選擇題

When the water produced from most evaporator is supplied for drinking purpose, it must be treated to ensure it is biologically pure and （）.

A.slightly acidic
B.slightly alkaline
C.no salty
D.slightly bitter

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