单项选择题
A.The construction of the vessel
B.The experience of the vessel's crew
C.The location of vessels detected by radar
D.All of the above
单项选择题 The Navigation Rules state that a vessel shall be operated at a safe speed at all times so that she can be stopped within（）.
单项选择题 The look-out must be able（）full attention to the（）of a proper look-out．
单项选择题 She（the vessel）shall if necessary（）and in any event navigate with extreme caution until danger of collision is over.