Flight level is a _______ of constant atmospheric pressure which is related to a specific pressure datum 1013.2 hpa.
A.standard
B.surface
C.height
D.number
正确答案是B
Flight level is a _______ of constant atmospheric pressure which is related to a specific pressure datum 1013.2 hpa.
A.standard
B.surface
C.height
D.number
正确答案是B