单项选择题
Preferred channel marks are colored with（）．
A.black and green bands B.red and green bands C.red and yellow bands D.yellow and green bands
单项选择题 Preferred channel marks are aids to navigation which all following marks other than（）．
单项选择题 In the absence of a route leading from seaward，the conventional direction of buoyage generally follows（）.
单项选择题 In regions where ice conditions prevail in the winter，（）.
