第6部分:完形填空 (第5l~65题,每题1分,共1 5分)8 y. {5 G2 M+ K, a/ X; P L% Q
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。
7 k3 G2 U& L$ U Earth’s Inner Core
1 B% {8 n! ]( K, O0 O6 ~0 u Scientists have long struggled to understand what lies at the planet’s center, Direct
8 V0 A; z9 u# A4 Z observation of its center is impossible,so researchers must_____(51)to other evidence.
. l8 Q" Y8 \0 j" ~0 K In 1889,a German scientist detected a severe earthquake in Japan.Geophysicists concluded
/ G0 h$ e/ Q* I" | that shock waves_____(52)jolts(晃动)from one side of Earth through the center to the
- _, W6 P- T+ j. s4 s8 L3 H other side.Then in 1936,Danish geophysicist Inge Lehmann studied the waves______(53)
8 H: r8 i" b" L) F/ b3 x' W- s to determine that within Earth’s core of molten(熔化了的)iron lies a solid inner core-but_____
; c8 U' k& B! a0 B3 B (54)that core was made of eluded(难倒)her.Other geophysicists quickly
* L! m% V. W8 x5 s6 V9 L9 Z determined that Lehmann’s inner core was composed mostly_____(55)iron. Since then,
% y; w. U. J" X2 p" r, M Lehmann’s discovery has_____(56)conventional Earth science.
$ V; d1 f7 r7 ]0 d7 w4 ` But now scientists are challenging traditional theory with new and radical _____(57)) E# {0 \) F, D1 k4 Q( j. A5 f3 n
For example,Earth’s center could actually contain an“inner core within the inner core,claim Ishii and colleague Adam Dziewonski.
) _% u4 |* C. E% j/ U6 S/ e 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,”says Dziewonski.
/ B" l' a! f0 @ Dziewonski and Ishii speculate that shortly_____(60) Earth formed around 4.8billion years ago,a giant asteroid(小行星)smashed into the young planet and nearly melted it. But Earth’s center didn’t quite melt;it______(61)mass as the planet cooled. The core within a core 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 is made not of iron,he claims
, Z* l+ g! s8 Z5 n8 S! a but a_____(64)of nickel and silicon Hemdon has a truly revolutionary notion:Within the nickel silicide(硅化物)inner core is also an“inner”inner core—an 8 km—wide ball of the element uranium.Uranium is radioactive.Hemdon thinks the uranium releases heat energy as its atoms_____(65)fission-split and crash into another in a chain reaction. In other words,we may live on top of a gigantic, “natural”nuclear power plant.
& P$ n; z2 h2 L( X! ? 51 A try B leave C turn D point
& J* t z0 d( M( H0 C* @3 ^! w 52 A create B receive C feel D overcome
; y5 t6 G: t; F2 @ 53 A work B solution C job D patterns
% `' s9 H5 v4 w. a; F 54 A whether B what C why D how. T3 C+ q8 j6 m" P4 Y- h
55 A from B within C of D to
+ ~$ D9 S2 X$ b3 s6 s* e* [ 56 A followed B dominated C restored D opposed
5 X- G3 Z8 i9 R6 ^* P1 o1 U 57 A ideas B demands C phenomena D movements
3 H: H# w4 `1 C* J 58 A things B acts C methods D records
( u2 [" z$ ?+ R# X3 |$ e 59 A taken B benefited C left D kept
7 o( }! l( v. k& y' v( n 60 A after B before C since D when, q7 d6 c% O% i9 S8 p
61 A expanded B modified C gained D melted: X) \$ F) d! u; r; C
62 A size B origin C structure D shape) F5 t {; r& K8 D) j t
63 A radical B traditional C classical D conventional- \3 T) ?+ D6 O8 M9 a" ~
64 A system B copy C model D compound
7 Z7 W1 X4 F4 }+ ?# H) A. @ 65 A charge B last C experience D show |