The term restricted visibility，when used in the Rules，refers to（）.

单项选择题The term power-driven vessel means（）in these Rules.

A.any sailing vessel with propelling machinery
B.any vessel propelled by machinery
C.any sailing vessel with or without machinery for propelling
D.any sailing vessel with propelling machinery not in use

单项选择题The steering and sailing rules for vessels in restricted visibility apply to vessels（）.

A.in sight of one another in fog
B.navigating in or near an area of restricted visibility
C.only if they are showing special purpose lights
D.only if they have operational radar

单项选择题The Rules state that certain factors are to be taken into account when determining safe speed. Those factors include（）.

A.state of wind，sea，and current，and the proximity of navigational hazards
B.maximum attainable speed of your vessel
C.temperature
D.aids to navigation that are available

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

A.radio communications that are available
B.maximum speed of your vessel
C.temperature
D.current

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