假设跑道的一个方向，由于飞行上的原因禁止用于起飞、着陆或者既不能用于起飞也不能用于着陆，则在NAIP中公布相应距离时用（）表示。

An air mass is a body of air that （ ） ．

A high cloud is composed mostly of （ ） ．

Low clouds usually consist almost entirely of （ ） ．

Fair weather cumulus clouds often indicate （ ） ．

The （ ） is a large body of air with fairly uniform temperature and moisture content.

Turbulence will occur when aircraft in flight encounter （ ）.

（ ） clouds indicate a fairly deep layer of unstable air. They contain moderate to heavy turbulence with icing and often develop into thunderstorms.

The term “embedded thunderstorms” indicates that （ ） ．

（ ） are found in altitudes associated with low, middle, and high clouds.

（ ） clouds are similar to cumulus clouds, except they have more vertical development.