单项选择题
An icebreaker assisting a vessel through an ice field would display a visual signal consisting of the code letter “E” (Echo) to signify that “（）”.
A.I am altering my course to starboard B.I am altering my course to port C.I am operating astern propulsion D.My vessel is stopped and making no way through the water
单项选择题 An example of an anchor which has a stock is a（）.
单项选择题 An example of a grade C product is（）.
单项选择题 An example of a grade B product is（）.
