单项选择题 Top and inner graduated borderlines of the chart are（）.

单项选择题 You are on watch at night in clear visibility and the vessel has just been anchored.The first thing that you should do after the anchor has been let go is to（）.

单项选择题 Most Navigation System equipment is（）from the bridge, a unique location that allows for a centralized,safe and efficient management of ship navigation.