仪表进近图的剖面图中下滑线上除标注最后进近的航迹方向外，ILS程序还应标出:（）。

（ ） are necessary for a substantial buildup of ice on an aircraft.

（ ） is the most dangerous type of structural icing.

（ ） stage of a thunderstorm might be considered the most violent.

（ ） are associated with the mature stage of the thunderstorm.

The cumulus stage of the thunderstorm is marked by （ ） ．

（ ） cloud is associated with fast-moving cold fronts.

（ ） generally produces the most violent flying weather.

（ ） is the most easily recognized discontinuity across a front.

The transition zone where two different airmasses meet is called a （ ） ．

An altostratus cloud is classified in the （ ） cloud group.