GWD30-Q11 to Q13:
First identified in 1969, komatiites
are Earth’s oldest known volcanic
rocks and contain three times as much
Line
magnesium as do most volcanic rocks.
(5)
This chemical composition suggests
that komatiites formed from the hottest lava known ever to have erupted:
a high concentration of magnesium changes the physical properties of
(10)
lava so that unusually high tempera-
tures would be required for the lava to exist as a liquid.
Komatiites’ discovery was surpris-
ing in light of then-current geological
(15)
theories about magmas, molten rock
that forms in the Earth’s mantle (the layer beneath the crust) and composes volcanic lava eruptions.
Prior to 1960, geologists Bowen and Hess disagreed
(20)
over whether or not the very high tem-
peratures needed to produce magmas
rich in magnesium could have existed
on Earth.
Hess suggested that the presence of water, probably released
(25)
from minerals decomposing in the
Earth’s mantle, might have meant that a high-magnesium magma could have existed at a lower temperature.
But Bowen showed experimentally that the
(30)
high temperatures were indeed nec-
essary.
By 1960, it was generally accepted that volcanic rocks with such
high levels of magnesium could not
exist, and thus the discovery of koma-
(35)
tiites changed geologists’ assumptions
about the characteristics of the Earth’s mantle around the time of the formation of komatiites, between 2.5 and 4 billion
years ago.
-------------------------------------------------------------------------------- Q11: Which of the following most accurately describes the organization of the passage? A Two divergent views of a scientific phenomenon are reconciled. B A phenomenon is described and its scientific significance is discussed. C The discovery of a scientific phenomenon is traced and its implications for further research are suggested. D A long-standing scientific theory is examined and recently discovered evidence is shown to support it.
E The ways in which a particular geological phenomenon is exceptional are detailed and classified.答案选b，我选了c，请问从哪里看出c不对呢
-------------------------------------------------------------------------------- Q12: Information in the passage suggests which of the following concerning the Earth’s mantle 2.5 to 4 billion years ago? A It contained magmas that were more significantly affected by the decomposition of minerals than are current-day magmas. B It contained a lower proportion of water that it contains today. C Its characteristics were accurately described by both Bowen and Hess. D Its temperature was sufficiently high to produce magmas with high magnesium content.
E Its total magnesium content then was roughly equivalent to its magnesium content today.答案选的d，我选了a，请问在那里定位是d呢 | 
