Meaning: Go into a building to steal something
Example: The burglars BROKE IN and stole the TV and video.
Meaning: Interrupt something
Example: I'm sorry to BREAK IN on your conversation, but there's a problem.
Meaning: Train a horse to be ridden
Example: It took ages to BREAK the horse IN.
Meaning: Carefully use new products until they are fully functional.
Example: I must watch my speed until I BREAK IN my new Volvo.