n.周长；周界；边缘
Work out how long the perimeter of the playground. 请你算一算体育场的周长是多少米?
Guards patrolled the perimeter of the airfield. 卫兵沿机场四周巡逻。
A fence marked the perimeter of the field. 一道篱笆标明了那块田地的周界。
The barbed wire fence round the perimeter discouraged intruders. 周围有铁丝网阻止了外人闯入。
