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

单项选择题 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 （）.

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