选词填空

Flying over a desert area in an airplane, two scientists looked down with trained eyes at trees and bushes. After an hour's 11 one of the scientists wrote in his book, "Look here for 12  metal. " Scientists in another airplane, flying over a mountain region, sent a 13  to other scientists on the ground, "Gold possible. " Walking across hilly ground, four scientists reported, "This ground should be searched for metals. " From an airplane over a hilly wasteland a scientist sent back by radio one word, "Uranium. "

None of the scientists had X-ray eyes: they had no 14   powers for looking down below the earth's surface. They were 15  putting to use one of the newest methods of 16  minerals in the ground—using trees and plants as 17   that certain minerals may lie beneath the ground on which the trees and plants are growing.

This newest method of searching for minerals is 18  on the fact that minerals deep in the earth may 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 branches from the trees. Roots were dug and put into boxes. Each bag and box was 20  marked. In a scientific laboratory the parts of the forest trees were burned to ashes and tested. Each small part was examined to learn whether there were minerals in it.

A. signs B. sufficiently C. locating D. affect

E. merely F. magic G. hints H. carefully

I. finding J. message K. flight L. probable

M. revealing N. based O. information

答案：11. K 12. L 13. J 14. F 15. E 16. C 17. A 18. N 19. D 20. H

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