单项选择题
A.Brown conical tower with white horizontal band in center of light on black pier
B.Red conical tower on brown cylindrical pier
C.White octagonal house on brown cylindrical pier
D.White conical tower，with brown band midway of height
单项选择题 Upon underwater（）by divers，there are no apparent（）on the bottom plates of the said vessel.
单项选择题 To reduce the number of strakes at the bow，two strakes are tapered and joined at their ends by a single plate. This plate is known as a（）.
单项选择题 Those ship’s tanks that are particularly important for trimming the ship are the（）.