perithallus

例句：

1. 1. The periphery of the city is surrounded by a large park.
   城市的外围是一片大型公园。
2. 2. The periphery of the world economy is in crisis.
   世界经济的边缘正面临危机。
3. 3. The periphery of the forest is densely populated.
   森林的边缘人口密集。