Countries that can launch lunar probes includes: ____.
A. The United States
B. Russia
China
D. India
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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
Which of following are right about the flap: ____.
A. Only opens when aircraft takes off
B. Only opens when aircraft lands
C. Opens when aircraft takes off and lands
D. Is a high lift device of aircraft
Corresponding auxiliary landing measures could use during landing process of airplane are: ____.
A. Open the drag parachutes
B. Open the air brake
C. Using arrester hook
D. Using thrust reverser
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