两自由度陀螺（）。

Industrial areas typically produce more fog since they （ ） ．

Hydroplaning is not likely to occur at high speeds on （ ） runways.

If frost is not removed from the wings before flight, it may cause （ ） ．

PIREPs are pilot reports of current （ ） ．

The strength and location of the jet stream is normally （ ） ．

A jetstream is defined as wind of （ ） ．

The radar summary chart is unique because it shows （ ） ．

（ ） are used for winds aloft forecasts.

A ceiling is defined as the height of the （ ） ．

（ ） is not included in a convective SIGMET.