通常说的机体是指（）。

The primary source of lift is （ ） ．

In general, the direction of lift is （ ） .

An airplane will not be in equilibrium （ ） ．

The four forces acting on an A/C will be in equilibrium when the aircraft is in （ ） level flight.

What affects indicated stall speed?

When the pilot pushes the control wheel forward, the elevators move （ ） and the nose of the aircraft moves （ ） ．

When pilots （ ） back on the wheel, the nose of the aircraft moves up.

（ ） is the main source of lift.

The wing of the airplane is shaped to take advantage of （ ） ．

The basic principle of pressure differential, also known as （ ） , says “as the velocity of a fluid (air) increases, its internal pressure decreases”.