Answer:
1. The train had already left
2. Worked/Had worked (choose which is fitting)
3. Completed
4. Looked for
5. Realized
6. Had not locked
7. Called
8. Had finished
9. Cleaned
10. Had arrived
11. Rang/Rung
12. Had answered
Step-by-step explanation:
Learn your past tense :D Goodluck and have a nice day!