单项选择题
A.not be regarded as a vessel
B.in general，keep well clear of all vessels
C.proceed at a slower speed than surrounding vessels
D.when making way，show the lights for a vessel not under command
单项选择题 The rules require which factor to be taken into account when determining safe speed（）.
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．