Fill in can, have to, may, might, must, need or should. 10. you … not vacuum the carpets because carol has already done it. 11. he … come to my party because he is ill. 12. he … go to the dentist when he has toothache. 13. it's not very important. you … not do it now. you … do it tomorrow. 14. …you speak many languages? 15. i don't know what i'm doing this weekend, but i … go to london. 16. smoking is very unhealthy. you … stop it. 17. you have got plenty of time. you … not hurry. 18. you … have a passport to visit most foreign countries.