Sure, here are the sentences filled in with suitable collocations:

1. John has one or two shirts to **hang out**.
2. It's **bad for** your health to be physically inactive.
3. You can **get in** with this set of keys.
4. Jack slipped on the banana peel and **fell down**.
5. **Allow to** cool for 20 minutes before serving.
6. Follow your own course, and **let** people talk.
7. Our friends **warned** us about the dog across the street.
8. She admitted **stealing** the money from her employers.
9. He needs more **help with** the project.
10. If you **get stuck**, click on Help.