Based on the context provided, here are the completed sentences:

1. The **police** successfully collected evidence of the crime and solved the case.
2. I tracked my order online and excitedly waited for the **delivery** in front of my house.
3. Every afternoon, I leave our trash bags outside for the **garbage collector** to collect.
4. The **firefighter** bravely saved the family from the burning building.
5. My neighbor is an **electrician** and he always helps me with different electrical issues.
6. The **artist** carefully used traditional techniques to create a unique piece of art.