The frequency band most used general aviation for two-way voice communications is （）. | 专业基础

单选题 ICAO adopted a phonetic alphabet to be used in radio transmissions in order to （）.

A、avoid misunderstandings of letters with similar sounds

B、avoid misunderstrandings of letters with different sounds

C、make letters easy to pronounce

D、make letters easy to remember

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单选题 The most significant limitation of VHF signals is that they （）.

A、travel only in a straight line

B、bounce off the ionosphere

C、follow the curvature of the earth

D、will not penetrate clouds

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单选题 A radio that combines a transmitter and recevier in one unit is called a （）.

A、simple system

B、unicom station

C、transceiver

D、duplex

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单选题 Constant attention to correct phraseology and procedures will （）.

A、result in their use becoming automatic

B、ensure a high standard of radio transmissions

C、contribute to the safety of operations

D、bring about all of the above

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单选题 If the transceiver has only 360-channel, （）.

A、full ATC service may not be available

B、delays can be expected

C、some services may not be received

D、all of the above may be possible

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单选题 An aircraft at 3,000 feet AGL and 69 miles from a specific VHF ground station may improve reception by （）.

A、descending to a lower altitude

B、climbing to a higher altitude

C、increasing the volume

D、decreasing the squelch setting

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单选题 A radio system that combines a transceiver for normal two-way communications and a navigational aid receiver into a single unit is called a （）.

A、duplex

B、two-way

C、multiplex

D、nav/com

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单选题 If the pilot wants to receive full ATC services, particularly in busy environment, （） transceivers are a necessity.

A、100-channel

B、180-channel

C、360-channel

D、720-channel

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