In the post office. Fill in the blanks.

Wstaw podane słówka w wolne miejsca w zdaniach.
registered to collect include the post code a mailbox
1. ‘I need to have a proof that I've sent this letter and the addressee will receive it.' ‘Then it has be a   letter.'
2. I must go to the post office   a package from my uncle who lives in Toronto.
3. When you address a letter you must   the addressee's name, address and above all   .
4. You don't have to go to the post office if you just want to send a postcard. You may put it into   .