Prepositions practice

Take a screenshot after each pls

1. start here
2. then here
3. then here
4. then here
5. then here
6. then here
7. then here
8. then here
9. then here
10. then here
11. then here
12. then here
13. then here
14. then here
15. then here

Explanations are here, only as required .