In determining safe speed，the Rules list all of the following as factors which must be taken into account EXCEPT the（）.

单项选择题In determining if risk of collision exists the following considerations shall be among（）.

A.these taken into calculation
B.those taking into account
C.that taken into account
D.those taken into account

单项选择题In a crossing situation on open waters，a sailing vessel shall keep out of the way of all the following vessels EXCEPT a vessel（）.

A.not under command
B.restricted in her ability to maneuver
C.engaged in towing
D.fishing

单项选择题If your vessel is underway in fog and you hear one prolonged and three short blasts，this is a （）.

A.vessel not under command
B.sailing vessel
C.vessel being towed (manned)
D.vessel being towed (unmanned)

单项选择题If there is sufficient sea room，alteration of（）may be the most effective action to avoid close-quarters situation.

A.speed and course
B.speed alone
C.course alone
D.speed or course

单项选择题If there is any doubt as to the proper operation of a radar，which statement is TRUE?（）.

A.Only a radar expert can determine if the radar is operating
B.All radars have indicator lights and alarms to signal improper operation
C.A radar range compared to the actual range of a known object can be used to check the operation of the radar
D.The radar resolution detector must be energized to check the radar