职称英语完形填空练习

学人智库 时间:2018-02-10 我要投稿
【www.unjs.com - 学人智库】

  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.

1.职称英语完形填空练习精选

2.2017职称英语考试完形填空真题练习

3.2017年职称英语完形填空练习(含答案)

4.2015职称英语《理工类》完形填空模拟练习

5.职称英语综合类完形填空练习题及答案

6.2016年职称英语完形填空练习题

7.职称英语综合B级完形填空练习

8.职称英语综合类完形填空练习及答案

9.2014职称英语《理工类》完形填空练习1

10.职称英语完形填空试题及答案