2014年职称英语考试理工类A级完形填空习题1
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.Geophysicists concluded
that shock waves_____(52)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______(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 quickly
determined 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)
For example,Earth’s center could actually contain an“inner core within the inner core,claim Ishii and 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,”says Dziewonski.