10. According to the passage, it is believed that oceanic islands are formed from
the same material as mantle xenoliths
the same material as the midocean ridge system
volcanic rocks from the upper mantle
incompatible elements percolating up from the lower mantle
mantle plumes arising from the lower mantle For the following question, consider each of the choices separately and select all that apply
11. It can be inferred from the passage that the sup-porters of the ―layered-mantle‖ theory believe which of the following?
□A The volcanic rocks on oceanic islands are composed of material derived from the lower part of the mantle.
□B The materials of which volcanic rocks on oceanic islands and midocean ridges are composed are typical of the layers from which they are thought to originate.
□C The differences in composition between volcanic rocks on oceanic islands and the midocean ridges are a result of different concentrations of incompatible elements.
12. In the context of the passage, unimaginatively is closest in meaning to
pedestrian
controversial
unrealistic
novel
paradoxical
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