The sentences that are correct with an appro sp hie

are 3,4.5.7. and 8
Are these correct?

1.Canada’s mens’ hockey team wins gold medals almost every year.
2. Lets forget that we tried to build a racing car because it’s been an awful experience for us and our friends.
3. The woman’s skin was raw where her boots had rubbed against her heels.
4. The country’s top leader attended the international conference last year.
5. It’s time to buy new books for our classes next semester.
6. Since the schools’ homework club began, my grades have improved.
7. The boy's father said the baseball was his son’s but we knew it was ours.
8. After three days’ worth of work, they completed the project.
9. There are three pieces’ of pie left,
10. We always have a big birthday party on my mothers birthday.

Right