The hotter the climate and the higher the airfield above sea level, the _______ the runways have to be.
A.shorter
B.more shorter
C.much shorter
D.longer
正确答案是D
The hotter the climate and the higher the airfield above sea level, the _______ the runways have to be.
A.shorter
B.more shorter
C.much shorter
D.longer
正确答案是D