单项选择题
A.Hydrometer
B.Hygrometer
C.Spectrometer
D.Barometer
单项选择题 ()is normally responsible for maintaining records of corrections to navigational charts and nautical publications.
单项选择题 The company should establish procedures by which()receive relevant information on the safety management system in working language or language understood by them.
单项选择题 When two power-driven vessels are meeting head-on and there is a risk of collision,each shall().