perimeter|perimeters

我们沿着公园的周边散步了一圈。

We walked around the ___perimeter of the park.

士兵们日夜巡逻，确保军事基地的周边安全。

Soldiers patrol day and night to secure the ___perimeters of the military base.

士兵们在营地周围设置了警戒线。

The soldiers set up a ___perimeter around the camp.