题目内容：

Flying over a desert in an airplane, two scientists looked down with trained eyes at trees and bushes．After an hour's flight, one of the scientists wrote in his notebook, "Look here for probable metal." 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 magic powers for looking down below the earth's surface．They were merely putting to use one of the newest methods of locating minerals in the ground -- using trees and plants as signs that certain minerals may lie under the ground on which the trees and plants are growing.

This newest method of searching for minerals is based on the fact that minerals deep in the earth may affect the kind of bushes and trees that grow on the surface.

At Watson Bar Creek, 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 carefully 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.

Study of the roots, branches and seeds showed no silver．But there were small amounts of gold in the roots and a little less gold in the branches and seeds．The seeds growing nearest to the tree trunk had more gold than those growing on the ends of the branches.

If the trees indicated that there was no gold in the ground, the scientists wouldn't spare money to pay for digging into the ground.

1.Scientists were flying over a desert or a hilly wasteland or a mountain region to _____.

A．train their eyes	B．study the trees
C．look for gold	D．search for minerals

2.The study of trees, branches and roots indicated that ______.

A．there were larger amounts of gold in the branches far from the tree trunk than in the seeds

B．there were smaller amounts of gold in the tree roots deep in the ground than in the branches

C．there were larger amounts of gold in the seeds growing closer to the tree trunk than in the seeds farther from it

D．there were larger amounts of gold in the branches than in the leaves on the ends of the branches

3.Which of the following is NOT mentioned as part of a tree that can help the searchers?

A．leaves

B．roots

C．branches

D．seeds

4.Which of the following might be the best title for this passage?

A．Scientists searching for treasure with special equipment.

B．New methods of doing geological study.

C．Gold could be found in trees and plants.

D．A new method of searching for minerals.