outer zone

例句：

1. 1. The outer zone of the planet is where life can't survive.
   这个星球的外部区域，生命无法生存。
2. 2.The outer zone of the city is where the pollution is worst.
   城市的外围是污染最严重的地方。
3. 3. The outer zone of the forest is where the animals live.
   森林的外围是动物们居住的地方。