give something back        
phrasal verb with give verb uk/ɡɪv/ us/ɡɪv/ gave | given
A2 还,归还
to return something to the person who gave it to you
  Has she given you those books back yet? 她把那些书还给你了吗? 
 - More examples
 - Make sure you give me the keys back when you've finished.
 - Give the bike back if you're not using it any more.
 - She liked the chair so much, she was reluctant to give it back.
 - You can borrow my CD, as long as you promise to give it back.
 - The museum gave the painting back to it rightful owner.