医用外科口罩的主要原材料是
A. 聚氯乙烯
B. 聚乙烯
C. 聚丙烯
D. 聚碳酸酯
The biggest advantage of inertial navigation is ____.
A. Highly accurate navigation
B. No accumulated error
Completely independent navigation
D. Good flight control capability
Which one of the world's four largest satellite navigation systems has the short message communication function? ____.
A. GPS navigation system
B. GLONASS navigation system
C. Beidou Navigation Satellite System
D. Galileo satellite navigation system
Scene matching navigation belongs to ____.
A. One-dimensional matching navigation
B. Two-dimensional matching navigation
C. Three-dimensional matching navigation
D. Four-dimensional matching navigation
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