insidiousPREP 1
GWD30-Q11 to Q13:
First identified in 1969, komatiites are Earth’s oldest known volcanic rocks and contain three times as much magnesium as do most volcanic rocks. 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 lava so that unusually high temperatures would be required for the lava to exist as a liquid.
Komatiites’ discovery was surprising in light of then-current geological theories about magmas, molten rock that forms in the Earth’s mantle (the layer beneath the crust) and compos volcanic lava eruptions. Prior to 1960, geologists Bowen and Hess disagreed over whether or not the very high temperatures needed to produce magmas rich in magnesium could have existed on Earth. Hess suggested that the prence of water, probably relead 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 high temperatures were indeed necessary. By 1960, it was generally accepted that volcanic rocks with such high levels of magnesium could not exist, and thus the discovery of komatiites 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.
兔子英语------------------------------------------------------------------purpo是什么意思
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 discusd.
C. The discovery of a scientific phenomenon is traced and its implications for further rearch are suggested.duet
mapex
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.
------------------------------------------------------------------
Q12:
Information in the passage suggests which of the following concerning the Earth’s mantle 2.5 to 4 billion years ago?
九年级英语教案
venus原唱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.
找外教一对一
----------------------------------------------------------------------
Q13:
Which of the following most accurately states the main point of the passage?
A. Komatiites provide information about rates of volcanic eruption between 2.5 and 4 billion years ago.
backpackB. Komatiites provide information about how the physical properties of lava in the Earth’s past compare with tho of current-day lava.
grandaddyC. Komatiites provide evidence that undermines Bowen’s experimental conclusions regar
ding the temperatures at which lava exists as a liquid.
D. Komatiites provide evidence that has changed geologists’ ideas about the characteristics of the Earth’s mantle between 2.5 and 4 billion years ago.
E.
Komatiites provide evidence that water in the Earth’s mantle may have reduced the temperature required for lava to exist as a liquid.
B
Q33-Q36: TTGWD11-Q24 to Q27:
Anole lizard species that occur together (sympatrically) on certain Caribbean islands occupy different habitats: some live only in the grass, some only on tree trunks, and some only on twigs. The species also differ morphologically: grass dwellers are slender with long tails, tree dwellers are stocky with long legs, twig dwellers are slender but stubby-legged. What is striking about the lizards is not that coexisting species differ in morphology and habitat u (such differences are common among cloly related sympatric species), but that the same three types of habitat specialists occur on each of four islands: Puerto Rico, Cuba, Hispaniola, and Jamaica. Moreover, the Puerto Rican twig species cloly rembles the twig species of Cuba, Hispaniola, and Jamaica in morphology, habitat u, and behavior. Likewi, the specialists for other habitats are similar across the islands. The prence of similar species on different islands could be variously explained. An ancestral species might have adapted to exploit a particular ecological niche on one island and then traveled over water to colonize other islands. Or this ancestral species might have evolved at a time when the islands were connected, wh
ich some of the islands may once have been. After the islands parated, the isolated lizard populations would have become distinct species while also retaining their ancestors’ niche adaptations. Both of the scenarios imply that specialization to each niche occurred only once. Alternatively, each specialist could have arin independently on each of the islands.
