The Rules state that certain factors are to be taken into account when determining safe speed. One of the factors is the（）.

单项选择题The rules require that a stand-on vessel SHALL take action to avoid collision when she determines that（）.

A.risk of collision exists
B.the other vessel will cross ahead of her
C.the other vessel is not taking appropriate action
D.collision cannot be avoided by the give-way vessel's maneuver alone

单项选择题The risk of collision shall be deemed to exist if the compass bearing of an approaching vessel （）.

A.did not appreciably change
B.does not appreciably change
C.do not appreciably change
D.not appreciably change

单项选择题The effectiveness of the action shall be carefully checked until the other vessel is finally （）.

A.past
B.clear
C.past or clear
D.past and clear

单项选择题Sailing vessels are stand-on over power-driven vessels except（）.

A.in a crossing situation
B.in a meeting situation
C.when they are the overtaking vessel
D.on the inland waters of the PR China

单项选择题Risk of collision is considered to exist if（）.

A.four vessels are nearby
B.a vessel has a steady bearing at a constant range
C.there is any doubt that a risk of collision exists
D.a special circumstance situation is apparent