【主题词汇过关】

1. waterfall 2. desert 3. pool 4. cliff 5. coast 6. coral 7. reef 8. bottom
9. surface 10. depth 11. climber 12. explorer 13. traveller 14. teammate
15. wonder 16. civilization 17. ambition 18. curiosity 19. development
20. risk 21. death 22. lifetime 23. unusual 24. changeable 25. risky 26. natural
27. alive 28. determined 29. northern 30. southern 31. northeastern
32. freshwater 33. cubic 34. dive 35. measure 36. survive 37. risk 38. attract
39. include 40. successfully 41. simply 42. bit by bit
43. square kilometre/kilometer