单项选择题
Every vessel shall（）maintain a proper look-out by sight and hearing as well as by all available means appropriate in prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.
A.in fog B.at night C.in narrow fairway D.at all times
单项选择题 During the day，a vessel picking up a submarine cable shall carry（）.
单项选择题 Dring a period of “whiteout”，you should expect which of the following（）.
单项选择题 Day-shapes must be displayed（）.
