单项选择题
A.first edition B.new edition C.revised edition D.reprint
Charts are subject to frequent correction according to ...
单项选择题Charts are subject to frequent correction according to （）.
A.Notices to Mariners B.Mariner's handbook C.Sailing Directions D.Guide to Port Entry
Contour elevations on this chart refer to heights in fe...
单项选择题Contour elevations on this chart refer to heights in feet above mean （）.
A.lower low water B.high water C.low water D.sea level
Navigational charts are subject to frequent changes，the...
单项选择题Navigational charts are subject to frequent changes，the important ones of which are promulgated by （）.
A.Admiralty Notices to Mariners B.Mariner's Handbook C.Catalogue D.Sailing Directions
