below ground

1.They built a bomb shelter below ground.

他们下修建了一个防空洞。

2.Their missile silos are below ground.

他们的导弹发射下。

3.Stem with much reduced leaf blades that function as rhizoids below ground, with or without tubers or rhizomes.

下面，起假根的用的茎具非常退化叶，有没有块茎根状茎。