subface

例句：

1. 1. The subsurface water is not visible to the naked eye.
   地下水在肉眼不可见。
2. 2.The subsurface layers of the earth are constantly being disturbed by human activities.
   地球的次级层不断地被人类活动所干扰。
3. 3. The subsurface geological structure plays a crucial role in the formation of mountains and valleys.
   次级地质结构在山脉和山谷的形成中起着至关重要的作用。