单项选择题
Which statement concerning GPS is TRUE（）.
A.It cannot be used in all parts of the world
B.There are 12 functioning GPS satellites at present
C.It may be suspended without warning
D.Two position lines are used to give a 2D fix
相关考题
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单项选择题
Which one of the followings does not limit the effective range of radar（）.
A.Pulse width
B.Pulse repetition frequency
C.Peak power
D.Target brightness -
单项选择题
Which of the following statements is TRUE regarding crane operations（）.
A.Radio communications allow the crane operator to disregard the use of hand signals
B.The crane operators and signalman must be familiar with the correct hand signals
C.The forward cranes can be operated from the bridge
D.The aft cranes can be operated from the aft steering station -
单项选择题
Which of the following statements is TRUE regarding automatic identification systems（AIS）（）.
A.AIS is a global tracking system that relies upon INMARSAT C service to communicate vessel position and other safety related information to similarly equipped vessels，aircraft and shore stations within the area
B.AIS is a short-range 3 cm X-band radar system that automatically sends a vessel's position and other safety related information to similarly equipped vessels，aircraft and shore stations within the area
C.AIS is a short-range VHF-FM system that automatically broadcasts a vessel's position and other safety related information frequently to similarly equipped vessels，aircraft and shore stations within the area
D.AIS is a one-way centrally managed system that requires the local VTS to send commands to instruct each vessel to broadcast position and other safety related information to similarly equipped vessels，aircraft and shore stations within the area
