八年级上册英语以字母c开头的单词包括：

1. calendar

2. care

3. careful

4. carefully

5. careless

6. cartoon

7. catch

8. caught

9. celebrate

10. certainly

11. character

12. cheeply

13. cheese

14. chocolate

15. choose

16. chose

17. clearly

18. close

19. coffee

20. college

21. comedy

22. common

23. concert

24. cook

25. comfortable

26. cabbage

27. cab

28. cabin

29. cable

30. cactus

31. cafe

32. cage

33. cake

34. calculator

35. calf

36. call

37. calm

38. camera

39. camp

40. can

41. canal

42. cancel

43. cancer

44. candle

45. candy

46. cane

47. cannon

48. canoe

49. canvas

50. cap

51. cape

52. capital

这些单词涵盖了不同的词性和用法，是八年级学生需要掌握的基础词汇。建议学生通过多种方式记忆这些单词，如制作单词卡片、进行单词接龙游戏等，以提高记忆效果。