1. burglary - burglaries
2. key - keys
3. knife - knives
4. knowledge - uncountable
5. air - uncountable (but if we talk about smb's manners, the plural form ("airs") is used; the sense, however, is absolutely different)
6. army - armies
7. formula - formulas / formulae
8. child - children
9. wife - wives
10. bottle - bottles
11. guitar - guitars
12. cloth - cloths (not to be confused with "clothes"!)
13. mouse - mice
14. tooth - teeth
15. tomato - tomatoes
16.video - videos
17. sheep - sheep
18. fruit - fruits (when we talk about the successful results of our work; the plural form is also used in specialised literature) or uncountable (more often)
19. plan - plans
20. tie - ties
21. house - houses
22. glass - glasses or uncountable (if we talk about the substance)
23. fruit - see above (№18)
24. path - paths
25. cigarette - cigarettes
26. bed - beds (countable, if we don't take some fixed expressions into account)
27. cat - cats
28. snow - uncountable in most cases; I don't want to burden your memory with too many details, I don't think it necessary to explain when it can be countable :)
29. holiday - holidays
30. cheese - uncountable or countable ("cheeses") (when we talk about different types of this food)
31. vertebra - vertebrae
32. boy - boys
33. child - children