单项选择题
A.对流层和平流层B.平流层和电流层C.电离层和外大气层D.对流层和电离层
A.10°B.16°C.27°D.35°
A.(n+1)(n+2)B.(n+1)(n+2)/2C.(n+2)(n+3)D.(n+2)(n+3)/2