Thrust value is constant and thrust directionvariable.
假定发动机推力大小为常值，方向可调。
2
An isogon is a contour line for a variable which measures direction.
等角线是用于测量方向的变量的轮廓线。
3
It defines a set of address Spaces for each pointer variable that is optimally efficient for the C8051 architecture, without any specific direction from the programmer.