单项选择题 A is the documentary attestation for the delivery of stores and spare parts（）

单项选择题 The purpose of treating the cooling water of the diesel engine is to（） Ⅰ. resist the scale formation in the cooling chamber Ⅱ.lubricate the engine part Ⅲ.increase thermal capacity Ⅳ.resist corrosion

单项选择题 When the ship, its main propulsion device equipped with clutch, arrived at the port and finished with the engine, the correct operation should be（）