Labium externum

例句：

1. 1.The bacteria live in the outer layer of the skin.
   细菌生活在皮肤的外层。
2. 2. The outer layer of the skin is responsible for protecting the body from harmful substances.
   皮肤的外层负责保护身体免受有害物质的伤害。
3. 3. The outer layer of the skin is also involved in the process of wound healing.
   皮肤的外层也参与伤口愈合的过程。