Answer:
1. Both of my friends study at medical college.
2. If you want to get to the supermarket you can take Either side of the street.
3. "Where can I find a bookstore?" "There are bookstores on Both sides of the street.
4. We were invited to two parties last week but we didn't go to Either.
5. Tom and I play chess regularly and Both of us play very well.
6. Lily couldn't decide which of the two dresses to choose, she liked Either.
7. She had a problem and asked two of her friends for help. They Both offered their help.
8. Ann is pleased as Both of her parents agree to go for a walk with her.
9. Would you like coffee or tea?" "Well, Either will do.
10. Ann has two sons and Both of them are at school.
11. These two students can Both speak good Spanish.
12. We were told that we could use Either side of the paper.