Answer:
1. prevent; accident
no helping verbs
2. appreciation; music
should, have
3. pass; potatoes
no helping verbs
4. waste; time
do
5. keep; coupons
did
6. collect; stamps
no helping verbs
7. invented; cotton gin
no helping verbs
8. answer; question
no helping verbs
9. picking; trophies
are
10. invented; steamboat
no helping verbs
(It's been awhile since I've done direct objects and helping so I hope I'm right!)