Above the land and water _ with a depth from 50 to 200 miles.
问题描述：
Above the land and water _ with a depth from 50 to 200 miles.
A.a layer of air is
B.is a layer of air
C.will a layer of air be
D.a layer of air will be
为啥
答
介词短语放在句首的倒装语序.
例：
Running through the city is there a river.
=There is a river running through the city.