The author is primarily concerned with______ [br] It can be inferred from the pa

游客2024-01-13  2

问题 The author is primarily concerned with______ [br] It can be inferred from the passage that which of the following is easiest to detect?

选项 A、A gold-quartz vein system originating in magmatic fluids
B、A gold-quartz vein system originating in meamorphic fluids
C、A gold deposit that is mixed with granite
D、A gold deposit that has shed alluvial gold
E、A gold deposit that exhibits chemical halos

答案 D

解析 The best answer is D. According to the passage, “Most of the gold deposits discovered during the original gold rushes were exposed at the Earth’s surface and were found because they had shed trails of alluvial gold that were easily traced by simple prospecting methods” (lines 9-12). By contrast, “most deposits not yet discovered have gone undetected because they are buried and have no surface expression” (lines 14-16), and the passage gives no indication that gold-quartz vein systems and gold deposits like those described in choices A, B, C, and E would have the kind of surface expression that would make them easy to detect.
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