Main differences between balloon and airship are ____.
A. Configuration
B. Motive power
C. Direction Control
D. Filling gases
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The advantages tiltrotor aircraft have over helicopter are ____.
A. Longer flight range
B. Lower cost
C. Simpler structure
D. Higher speed
Countries that can launch lunar probes includes: ____.
A. The United States
B. Russia
China
D. India
Main advantages of space shuttle over spacecraft are ____.
A. Large payload
B. Easy to take-off and landing
C. Reusable
D. More functional
Main functions of landing gear are: ____.
A. Is an important load-bearing component
B. Absorbing impact energy during the landing process
C. Withstanding payloads
D. Taxiing and controlling on the ground
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