Aircraft lighter than air lifts off by ____.
A. Static buoyancy generated by air
B. Aerodynamics
C. Hot air
D. Helium
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The main difference between rotorcraft and helicopter is that ____.
A. They have different fuselages
B. They have different rotor
C. They have different way to drive the rotor
D. If their rotor can generate lift or not
The “Cassini-Huygens” Saturn probe took ____ to reach the orbit around Saturn.
A. 7 months
B. 11months
C. 7 years
D. 11 years
The most widely used manned space vehicle is ____.
A. Manned spacecraft
B. Space shuttle
C. Aero-space plane
D. Carrier rocket
Two main landing gears at the rear of the aircraft's center of gravity, with a nose landing gear at the front is the layout structure of ____.
A. Tail-wheel tricycle landing gear
B. Nose-wheel tricycle landing gear
C. Bicycle landing gear
D. Multiple-wheel-and-struts landing gear
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