This newest method of searching for minerals is 18 on the fact that minerals deep in the earthmay 19 the kind of bushes and trees that grow on the surface.

　　At Watson Bar Creek, a brook six thousand feet high in the mountains of British Columbia,Canada, a mineral search group gathered bags of tree seeds. Boxes were filled with small branchesfrom the trees. Roots were dug and put into boxes. Each bag and box was 20 marked. In a scientificlaboratory the parts of the forest trees were burned to ashes and tested. Each small part wasexamined to learn whether there were minerals in it.

　　參考答案：

　　II. K 12. L 13. J 14. F 15. E 16. C 17. A 18. N 19. D 20. H