第6部分：完形填空(第51～65题，每题1分，共15分)
阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案，涂在答题卡相应的位置上。
Earth's Inner Core
Scientists have long struggled to understand what lies at the planet's center, Direct observation of its center is impossible, so researchers must (51)_________ to other evidence.
In 1889, a German scientist detected a severe earthquake in Japan. Geophysicistsconcluded that shock waves (52) _________ jolts (晃动) from one side of Earth through the centerto the other side. Then in 1936, Danish geophysicist Inge Lehmann studied the waves (53)_________to determine that within Earth's core of molten (熔化了的) iron lies a solid inner core-but(54) _________that core was made of eluded (难倒) her. Other geophysicists quicklydetermined that Lehmann's inner core was composed mostly(55)_________iron. Since then,Lehmann's discovery has (56) _________conventional Earth science.
But now scientists are challenging traditional theory with new and radical (57)_________. Forexample, Earth's center could actually contain an "inner core within the inner core, claim Ishiiand colleague Adam Dziewonski. Analyzing hundreds of thousands of earthquake wave(58)_________, they maintain that the inner core has at its heart a tiny, even more solid sphere(球体) . This sphere "may be the oldest fossil (59)_________ from the formation of Earth," saysDziewonski.
Dziewonski and Ishii speculate that shortly (60)_________ earth formed around 4.8billionyears ago, a giant asteroid (小行星) smashed into the young planet and nearly melted it. ButEarth's center didn't quite melt; it (61) _________ mass as the planet cooled. The core within acore may be the kernel (核心) that endured. "Its presence could change our basic ideas about the(62) _________ of the planet, " Dziewonski says idea is tame (温和的) compared to the(63)_________ theories of independent geophysicist J. Marvin Herndon. Earth's inner core ismade not of iron, he claims but a(64)_________ of nickel and silicon Hemdon has a trulyrevolutionary notion: Within the nickel silicide (硅化物) inner core is also an "inner" innercore an 8 km -- wide ball of the element uranium. Uranium is radioactive. Hemdon thinksthe uranium releases heat energy as its atoms(65)_________ fission-split and crash into another in achain reaction. In other words, we may live on top of a gigantiC. "natural" nuclear powerplant.
请在第__(51)__处填上正确答案。
A.try
B.leave
C.turn
D.point
52、请在第__(52)__处填上正确答案。
A.create
B.receive
C.feel
D.overcome
53、请在第__(53)__处填上正确答案。
A.work
B.solution
C.job
D.patterns
54、请在第__(54)__处填上正确答案。
A.whether
B.what
C.why
D.how
55、请在第__(55)__处填上正确答案。
A.from
B.within
C.of
D.to
56、请在第__(56)__处填上正确答案。
A.followed
B.dominated
C.restored
D.opposed
57、请在第__(57)__处填上正确答案。
A.ideas
B.demands
C.phenomena
D.movements
58、请在第__(58)__处填上正确答案。
A.things
B.acts
C.methods
D.records
59、请在第__(59)__处填上正确答案。
A.taken
B.benefited
C.left
D.kept
60、请在第__(60)__处填上正确答案。
A.after
B.before
C.since
D.when
61、请在第__(61)__处填上正确答案。
A.expanded
B.modified
C.gained
D.melted
62、请在第__(62)__处填上正确答案。
A.size
B.origin
C.structure
D.shape
63、请在第__(63)__处填上正确答案。
A.radical
B.traditional
C.classical
D.conventional
64、请在第__(64)__处填上正确答案。
A.system
B.copy
C.model
D.compound
65、请在第__(65)__处填上正确答案。
A.charge
B.last
C.experience
D.show
