单项选择题
Which one is NOT the ‘clear grounds’ for a more detailed inspection?（）
A.the master and the chief engineer are unable to communicate effectively B.serious corrosion on the hull C.damaged sanitary pump D.one page missing in the oil record book
单项选择题 The shipboard oil pollution emergency plan will be invalid after （）
单项选择题 （）connectors hold best if a wire is accidentally pulled or a connection becomes loose.
单项选择题 （）are used to digest the sewage to produce innocuous sludge in a biological sewage treatment plant.
