What is the past perfect tense of do?

Related questions

1. What is an example of past tense?
2. What is the difference between past and present perfect tense?
3. What are the rules of past tense?
4. What is past tense examples?
5. Has decided or had decided?
6. What is an example of past perfect tense?
7. What is perfect aspect example?
8. Has or had taken?
9. Has been decided?
10. What is the formula of past simple tense?

Tags

1. #point
2. #regular
3. #finished
4. #perfect
5. #happened
6. #action
7. #irregular
8. #either
9. #participle
10. #before
11. #completed
12. #something
13. #tense
14. #indicates
15. #formed
16. #which
17. #perfected