Distilled water is now largely used on board, this may be corrosive (due to presence of dissolves CO₂) and （） to the taste.

The domestic fresh water pump starters are controlled by pressure switches which operate when the pressure in the tank varies within predetermined limits as water is drawn offThe word “which” means （）.

A.starters
B.pressure switches
C.pressure
D.water

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In general, domestic flesh water tank kept under pressure by an external supply of （）.

A.forced circulating pump
B.compressed air
C.gravity tank
D.bead tank

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