Sure! Here are the sentences with the appropriate prepositions filled in:

1. I talked **to** Mary **at** 10 am **on** Sunday morning.
2. I go to school every day **from** Monday **to** Friday, **at** 7 am **to** 4:30 pm.
3. The course begins **on** 2nd January and usually ends **in** April.
4. Let’s meet **on** Saturday afternoon **at** half past two.
5. I waited **until** 10:30, but she didn't come.
6. Sometimes I study and listen **to** music **at** the same time.
7. I live **in** a small village **in** the countryside.
8. I like living **in** the city; the city is very different **from** life **in** the countryside.
9. How usually goes **to** the library **by** bike? She likes reading **in** her free time.
10. History and geography books are **on** the shelves **in** the library.
11. We are going **to** the zoo **this** Sunday?
12. Modern graffiti began **in** big cities **in** the United States **in** the 1970s.
13. She is talking **on** the phone **to** her mother **about** her new school.
14. My sister has the same hobby **as** me.
15. His parents are worried **about** his study.

Feel free to reach out if you have any more questions!