现行的两种格式航图的主要区别在于？what is the main difference between the two format chart？
A.高距比表的位置和地速下降率表的单位。position of the altitude-distance chart and unit of the ground speed-vertical speed
B.下降梯度的变化。the change of descend gradient
C.进近程序的变化。the change of approach procedure
正确答案是A