"S" or no "s"? Write the correct form.

1. Susan writes. 2. Mark and Steve run. 3. My sister eats. 4. The mouse eats. 5. They drive. 6. You go. 7. My friend and I walk. 8. I drink. 9. You and your brother travel. 10. We wake up. 11. She wakes up. 12. The horse sleeps. 13. He jumps. 14. My father and my brother play. 15. We sing.