The VOR provides better accuracy and reliability than NDB because its signals are less ________________________around terrains and suffers less _____________________ from thunderstorms.
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VOR stations operate in the VHF band which limits their range to ____________________.
An extensive network of ground stations is need to provide __________________along the main air routes.
“人工智能”(artificial intelligence,AI)这一概念,公认是( )年在达特茅斯会议上被首次提出的。
A. 1978
B. 2001
C. 2004
D. 1956
( )年被称为是人工智能发展元年。
A. 2016
B. 2008
C. 2006
D. 1990
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