在飞机降落前，机组人员需要降低机舱内的气压。

The crew needs to ___depressurize the cabin before the plane lands.

飞机在高空突然开始减压，乘客们必须迅速戴上氧气面罩。

The airplane started to ___depressurize at high altitude, and passengers had to quickly put on oxygen masks.