三、什麼是泵？根據用途來分類，船上有那些泵？請列舉出它們的名稱。（20 分）

⑵ The fresh water cooling system is a closed cooling system, in which the fresh water first passes the fresh water cooler, where it is cooled by sea water, and then is circulated through the cooling water jackets of the main engine by fresh water pump to cool cylinder liners, cylinder heads and exhaust valves.