For the 19th question, it's visito.
For the 20th question, it's comparado.
...and then for the last question, you need to write 3 brief sentences telling a place you traveled and something you bought there, who you bought it for, and where you bought it. But in the third sentence, you need to use a direct object pronoun to replace your item. If that makes any since.
Example:
I went to New York and bought my first phone for myself at the store.
Fui a Nueva York y me compre mi primer telefono en la tienda.
I hope this helps you. :)