Cho dạng quá khứ của các động từ sau.
1. do _______________ 11. buy ________________________
2. teach _______________ 12. have ________________________
3. send _______________ 13. take ________________________
4. spend _______________ 14. go ________________________
5. begin _______________ 15. make ________________________
6. cut _______________ 16. think ________________________
7. put _______________ 17. see ________________________
8. give _______________ 18. eat ________________________
9. write _______________ 19. sing ________________________
10. be _______________ 20. wear ________________________