机随气流升降并保持飞机的姿态，这样机体承受的压力将是最小的。
(22)How can an airplane produce the same lift in ground effect as when out of ground effect?
? ? ?
A．The same angle of attack. B．A lower angle of attack. C．A higher angle of attack.
正确答案：B
(23)What is a purpose of flight spoilers?
? ? ?
A．Increase the camber of the wing.
B．Reduce lift without increasing airspeed. C．Direct airflow over the top of the wing at high angles of attack.
正确答案：B
(24)For which purpose may flight spoilers be used?
? ?
A．Reduce the wings' lift upon landing. B．Increase the rate of descent without increasing aerodynamic drag.
?
C．Aid in longitudinal balance when rolling an airplane into a turn.
正确答案：A
(25)Which is a purpose of ground spoilers
? ? ?
A．Reduce the wings lift upon landing B．Aid in rolling an airplane into turn. C．Increase the rate of descent with out gaining airspeed.
正确答案：A
(26)What is the purpose of a control tab?
?
A．Move the flight controls in the event of manual reversion.
?
B．Reduce control forces by deflecting in the proper direction to move a primary flight control.
?
C．Prevent a control surface from moving to a full-deflection position due to aerodynamic forces.
正确答案：A
(27)Which is a purpose of wing-mounted vortex generators?
?
A．Reduce the drag caused by supersonic flow over portions of the wing
?
B．Increase the onset of drag divergence and aid in aileron effectiveness at high speed
?
C．Break the airflow over the wing so the stall will progress from the root out to the tip of the wing
正确答案：A
(28)What is the purpose of a servo tab？
?
A．Move the flight controls in the event of manual reversion.
?
B．Reduce control forces by deflecting in the proper direction to move a primary flight control.
?
C．Prevent a control surface from moving to a full-deflection position due to aerodynamic forces.
正确答案：B
(29)What is the purpose of an elevator trim tab?
?
A．Provide horizontal balance as airspeed is increased to allow hands-off flight.
?
B．Adjust the speed tail load for different airspeeds in flight allowing neutral control forces.
?
C．Modify the downward tail load for various airspeeds in flight eliminating flight-control pressures.
正确答案：C
(30)Which direction from the primary control surface does a servo tab move?
? ? ?
A．Same direction. B．Opposite direction.
C．Remains fixed for all positions.
正确答案：B
(31)Which direction from the primary control surface does an anti-servo tab move?
? ? ?
A．Same direction. B．Opposite direction.
C．Remains fixed for all positions.
正确答案：A