What's the structure of this word / sentence? 搬进、走出、跑回 What's the structure of these words? 搬进、走出、跑回......

I think both 搬 and 进 can be verbs but when used together, it means 'move in'.

What's the relationship between the two characters in phrases like those? 

For example, only 搬 is the verb in the sentence ‘我们搬进了一幢楼房’，but not ‘进’，what is the role of ‘进’ in the sentence?

Thank you!
The “进” part is called directional complement.


  Rather simply, as we do in English, you can add a directional word to the verb, to describe where the verb is going. The most common words to indicate a direction are:
  
  
  上, up and 下, down &lt;== notice how they kind of look like arrows?
  进, in and 出, out
  过, to cross over
  起, up
  回 to come back.
  到 (to arrive) to
  


So, “搬进” is “move in/into”, “走出” is “walk out (of)”, “跑回” is “run back to”.