单项选择题
A.a blast of from five to seven seconds' duration B.a blast of from five to six seconds' duration C.a blast of from four to six seconds' duration D.a blast of from six to seven seconds' duration
The Rules state that risk of collision shall be deemed ...
单项选择题The Rules state that risk of collision shall be deemed to exist（）．
A.Whenever two vessels approach from opposite directions B.If the bearing of an approaching vessel does not appreciably change C.Whenever a vessel crosses ahead of the intended track of another vessel D.If one vessel approaches another so as to be overtaking
The Rules state that a seaplane shall（）.A.not be regard...
单项选择题The Rules state that a seaplane shall（）.
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
The rules require which factor to be taken into account...
单项选择题The rules require which factor to be taken into account when determining safe speed（）.
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
