An on glide slope indication from a four-light PAPI is _______ .
A.four white lights
B.four red lights
C.four green lights
D.two white and two red lights
正确答案是D
An on glide slope indication from a four-light PAPI is _______ .
A.four white lights
B.four red lights
C.four green lights
D.two white and two red lights
正确答案是D