单项选择题
A.a service tank
B.a settling tank
C.an expansion tank
D.a double bottom tank
单项选择题 In a central cooling system, used in some modem ships, sea water is supplied to cool （）which will circulate to other individual cooler, greatly reducing the corrosion problems.
单项选择题 In a central cooling system, used in some modem ships, sea water is supplied to cool （）which will circulate to other individual cooler, greatly reducing the corrosion problems.
单项选择题 In a （） engine the charge of air in the cylinder before compression commences is above atmospheric pressure.