How many rivers are there in europe? надо ли артикль the тут ставить?

open - opened - opened. это правильный глагол, поэтому просто присоединяешь окончание -ed.

1) i have not been to the zoo yet.

2)i've never been to the africa.

3) mr.rambler has never been to kenya.

4) my brother has not seen a fox in the wild yet.

5) they have not travelled to australia yet.

6)she has not touched a kangaroo yet.