单项选择题
A vessel constrained by her draught may，in addition to the lights prescribed for power-driven vessels in Rule 23，exhibit where they can best be seen（）or a cylinder.
A.two all-round red lights in a vertical line B.three all-round red lights in a vertical line C.two all-round yellow lights in a vertical line D.three all-round green lights in a vertical line
单项选择题 A vessel conducting mine clearing operations will show（）.
单项选择题 A vessel being towed will show（）.
单项选择题 A vessel being towed astern shall show at night（）.
