Scientists have long struggled to understand what lies at the planets center. Direct observation of its center is impossible, so researchers must (1) to other evidence.
In 1889, a German scientist detected a severe earthquake in Japan. Geophysicists concluded that shock waves (2) jolts (晃动) from one side of Earth through the center to the other side. Then in 1936, Danish geophysicist Inge Lehmann studied the waves (3) to determine that within Earths core of molten (熔化了的) iron lies a solid inner core - but (4) that core was made of eluded (难倒) her. Other geophysicists quickly determined that Lehmanns inner core was composed mostly (5) iron. Since then, Lehmanns discovery has (6) conventional Earth science.
But now scientists are challenging traditional theory with new and radical (7). For example, Earths center could actually contain an inner core within the inner core, claim Ishii and colleague Adam Dziewonski.
Analyzing hundreds of thousands of earthquake wave (8), 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 (9) from the formation of Earth, says Dziewonski.
Dziewonski and Ishii speculate that shortly (10) Earth formed around 4.8 billion years ago, a giant asteroid (小行星) smashed into the young planet and nearly melted it. But Earths center didnt quite melt; it (11) 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 (12) of the planet, Dziewonski says.
Dziewonskis idea is tame (温和的) compared to the (13) theories of independent geophysicist J. Marvin Herndon. Earths inner core is made not of iron, he claims, but a (14) of nickel and silicon. Herndon 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. Herndon thinks the uranium releases heat energy as its atoms (15) fission-split and crash into one another in a chain reaction. In other words, we may live on top of a gigantic, natural nuclear power plant.
1 A try B leave C turn D point
2 A create B receive C feel D overcome
3 A work B solution C job D patterns
4 A whether B what C why D how
5 A from B within C of D to
6 A followed B dominated C restored D opposed
7 A ideas B demands C phenomena D movements
8 A things B acts C methods D records
9 A taken B benefited C left D kept
10 A after B before C since D when
11 A expanded B modified C gained D melted
12 A size B origin C structure D shape
13 A radical B traditional C classical D conventional
14 A system B copy C model D compound
15 A charge B last C experience D show
参考答案:
1. C 2. A 3. D 4. B 5. C
6. B 7. A 8. D 9. C 10. A
11. C 12. B 13. A 14. D 15. C
2016届高考英语二轮题型专题方略课件:专题2 完形填空(通用版)
2016届高考英语二轮题型专题方略课件:专题4 语法填空和短文改错 第3讲 语法专题 10 特殊句式(通用版)
2016届高考英语二轮题型专题方略课件:专题1 阅读理解 第4讲 主旨大意题(通用版)
2016届高考英语二轮复习专项练习:Book4 4.1 (新人教版)
2016届高考英语二轮复习专项练习:Book4 4.5 (新人教版)
2016届高考英语二轮复习针对训练:专题1 阅读理解 第3讲 词义猜测题(通用版)
2016届高考英语二轮复习专项练习:Book4 4.3 (新人教版)
2016届高考英语二轮复习专项练习:Book3 阶段综合·检测训练(新人教版)
2016届高考英语二轮题型专题方略课件:专题1 阅读理解 第2讲 推理判断题(通用版)
2016届高考英语二轮题型专题方略课件:专题1 阅读理解 第5讲 篇章结构题(通用版)
2016届高考英语二轮题型专题方略课件:专题4 语法填空和短文改错 第3讲 语法专题 9 并列句和状语从句(通用版)
2016届高考英语二轮题型专题方略课件:专题4 语法填空和短文改错 第3讲 语法专题 3 形容词和副词(通用版)
2016届高考英语二轮复习专项练习:Book3 3.5 (新人教版)
2016届高考英语二轮复习专项练习:Book5 5.5 (新人教版)
2016届高考英语二轮复习专项练习:Book5 5.4 (新人教版)
2016届高考英语二轮复习针对训练:专题4 语法填空和短文改错 第3讲 语法专题 5 动词的时态、语态和语气(通用版)
2016届高考英语二轮复习针对训练:专题4 语法填空和短文改错 第3讲 语法专题 2 代词和介词(通用版)
2016届高考英语二轮复习专项练习:Book3 3.3 (新人教版)
2016届高考英语二轮复习针对训练:专题2 完形填空(通用版)
2016届高考英语二轮复习专项练习:Book5 5.3 (新人教版)
2016届高考英语二轮复习专项练习:Book5 阶段综合·检测训练(新人教版)
2016届高考英语二轮题型专题方略课件:专题4 语法填空和短文改错 第3讲 语法专题 8 名词性从句(通用版)
2016届高考英语二轮复习专项练习:Book5 5.2 (新人教版)
2016届高考英语二轮语法复习课件:专题10 特殊句式(人教版)
2016届高考英语二轮题型专题方略课件:专题4 语法填空和短文改错 第3讲 语法专题 6 情态动词(通用版)
2016届高考英语二轮复习针对训练:专题4 语法填空和短文改错 第3讲 语法专题 4 动词的时态、语态和语气(通用版)
2016届高考英语二轮题型专题方略课件:专题3 书面表达(通用版)
2016届高考英语二轮题型专题方略课件:专题1 阅读理解 第3讲 词义猜测题(通用版)
2016届高考英语二轮复习专项练习:Book3 3.2 (新人教版)
2016届高考英语二轮复习针对训练:专题4 语法填空和短文改错 第3讲 语法专题 9 并列句和状语从句(通用版)