internal inner ring

例句：

1. 1. The inner workings of the machine are fascinating to me.
   这台机器的内部构造让我着迷。
2. 2. She kept her innermost secrets locked away.
   她把最深处的秘密锁了起来。
3. 3. The book's inner meaning is not easily understood by everyone.
   这本书的内在含义不是每个人都能理解的。