Earths Inner Core
Scientists have long struggled to understand what lies at the planets center, Direct observation of its center is impossible,so researchers must_____to other evidence.
In 1889,a German scientist detected a severe earthquake in Japan.Geophysicists concluded that shock waves_____joltsfrom one side of Earth through the center to the other side.Then in 1936,Danish geophysicist Inge Lehmann studied the waves______ to determine that within Earths core of molteniron lies a solid inner core-but_____ that core was made of eludedher.Other geophysicists quickly determined that Lehmanns inner core was composed mostly_____iron. Since then, Lehmanns discovery has_____conventional Earth science.
But now scientists are challenging traditional theory with new and radical _____ For example,Earths center could actually contain aninner core within the inner core,claim Ishii and colleague Adam Dziewonski.
Analyzing hundreds of thousands of earthquake wave _____,they maintain that the inner core has at its heart a tiny, even more solid sphere . This spheremay be the oldest fossil____from the formation of Earth,says Dziewonski.
Dziewonski and Ishii speculate that shortly_____ Earth formed around 4.8billion years ago,a giant asteroidsmashed into the young planet and nearly melted it. But Earths center didnt quite melt;it______mass as the planet cooled. The core within a core may be the kernelthat endured.Its presence could change our basic ideas about the_____ of the planet,Dziewonski says idea is tamecompared to the_____theories of independent geophysicist J.Marvin Herndon.Earths inner core is made not of iron,he claims but a_____of nickel and silicon Hemdon has a truly revolutionary notion:Within the nickel silicideinner core is also aninnerinner core-an 8 km-wide ball of the element uranium.Uranium is radioactive.Hemdon thinks the uranium releases heat energy as its atoms_____fission-split and crash into another in a chain reaction. In other words,we may live on top of a gigantic, naturalnuclear power plant.
51 A try B leave C turn D point
52 A create B receive C feel D overcome
53 A work B solution C job D patterns
54 A whether B what C why D how
55 A from B within C of D to
56 A followed B dominated C restored D opposed
57 A ideas B demands C phenomena D movements
58 A things B acts C methods D records
59 A taken B benefited C left D kept
60 A after B before C since D when
61 A expanded B modified C gained D melted
62 A size B origin C structure D shape
63 A radical B traditional C classical D conventional
64 A system B copy C model D compound
65 A charge B last C experience D show
答案:
51 C turn to other evidence:寻求其他证据。Tum to属固定搭配。
52 A create jolts:造成震动。其他几个选项意思不符。
53 D wayespatterns:波浪的形状。科学家通过研究震波的形状了解地球的情况。
54 B 此处的意思是地心是由什么构成的难倒了她。这里应使用what构成名词性从旬,作主语。
55 C compose of:由组成。固定短语。
56 B dominate:占统治地位,支配。Lehamann的发现在传统地球科学领域占统治地位。
57 A 此处的意思是:现在的科学家正用新的、激进的观点挑战传统的理论。本题只有填ideas才符合本句的意思。
58 D 此处填records,本句的意思是:通过分析数十万次地震波的记录,他们认为。其他几个选项与句意不符。
59 C left:留下来的。此处的意思是:这一球体可能是地球形成时留下来的最古老的化石。
60 A 依据上下文,应用afte~句子意思才讲得通。
61 C gain:获取。gained mass as the planet cooled:在星球变冷的过程中,它逐渐获得了质量。
62 B 本文主要谈地球起源问题,故此处应填ongm.
63 A 本句前面出现的一个词是tame,与之对应,应该是radical.
64 D nickel和silicon的混合物,compound:混合物。
65 C fission-split:裂变。经历裂变,用动词experience.
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