单项选择题
You may find the time of slack water after low water in a certain port from（）.
A.Deadweight Scale B.Tide Tables C.Notices to Mariners D.Table of Azimuth
单项选择题 The satellite system of GAMDSS comprise（）.
单项选择题 The terrestrial system of GMDSS consists of（）.
单项选择题 An（）indicates that there is imminent risk for navigation.
