help me, please! Choose the correct preposition of time to complete the sentences.

1. They had a big party (on/ in) their anniversary.
2. It rained cats and dogs (since/ for) two hours last night.
3. Wait here. I’ll be back (at/ in) ten minutes.
4. He should return (on/ by) the end of July.
5. We always go to church (on/ at) Christmas.
6. Did they invent the Internet (in/ for) the 1960s?
7. I’m calling to confirm the meeting (by/ on) May 15.
8. We were waiting for you (for/ at) an hour.
9. They don’t talk to each other (in/ during) meals.
10. I can complete the report (by/ on) 4 pm. At 4 pm it will be finished.