Choose the correct options

1. She decided to give
   [up|out|back]
   smoking.
2. Look at her new hair[cut|note|ache]! It is really nice.
3. You
   [mustn't|can't|don't have to]
   stay here after the results have been announced.
4. You shouldn't worry
   [about|on|for]
   your exam results. I think you'll get a good mark.
5. [Toothache|Toothpaste|Toothpaper]
   is a substance you use to brush your teeth.
6. I know that John is in his office now. He
   [must|have to|should]
   be working.
7. Stop blaming my friend
   [about|on|for]
   copying your notes. He didn't do it!
8. Teenagers
   [might|mustn't|should]
   chat online carefully.
9. A kind-hearted person always cares
   [about|at|off]
   his friends and relatives.
10. Banks warn their clients not to give
    [back|up|out]
    their passwords to anyone.