这台机器内部有大量复杂的电路。

This machine has many complex circuits ___internally.

尽管她表面平静，内心却在激烈斗争。

Though she appeared calm, she was fighting ___internally.

公司决定内部处理这次投诉，不向外界公开。

The company decided to handle the complaint ___internally without making it public.