极地大陆气团（Polar continental air mass）：（），空气层结稳定。

A:干燥、低温、天气晴朗 B:低温、潮湿、多阴天 C:干燥、低温、气层不稳定 D:干燥、低温、常阴天

极点排序法(polar ordination，PO)

The polar regions are generally covered with ice and snow（　）.

A:areas B:rocks C:mountains D:seas

The polar regions are generally covered with ice and snow.

A:areas B:rocks C:mountains D:seas

The polar {{U}}regions{{/U}} are generally covered with ice and snow.

A:areas B:rocks C:mountains D:seas

The polar regions are generally covered with ice and snow.

A:areas B:rocks C:mountains D:seas

The polar lights, one of the most unusual phenomena in nature, is beautiful to behold.

A:view B:relate C:sketch D:withhold

极地大陆气团（ Polar continental air mass ）： ________，空气层 结稳定。

A:干燥、低温、天气晴朗 B:低温、潮湿、多阴天 C:干燥、低温、气层不稳定 D:干燥、低温、常阴天"