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  3. The coastlines on the two sides of the Atlantic Ocean present a notable parallelism: the eastern- most region of Brazi

The coastlines on the two sides of the Atlantic Ocean present a notable parallelism: the eastern- most region of Brazi

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问题         The coastlines on the two sides of the Atlantic
     Ocean present a notable parallelism: the eastern-
     most region of Brazil, in Pernambuco, has a con-
Line vexity that corresponds almost perfectly with the
(5) concavity of the African Gulf of Guinea, while
     the contours of the African coastline between Rio
     de Oro and Liberia would, by the same approxi-
     mation, match those of the Caribbean Sea.
         Similar correspondences are also observed in
(10) many other regions of the Earth. This observation
     began to awaken scientific interest about sixty
     years ago, when Alfred Wegener, a professor at
     the University of Hamburg, used it as a basis for
     formulating a revolutionary theory in geological
(15) science. According to Wegener, there was origi-
     nally only one continent or land mass, which he
     called Pangea. Inasmuch as continental masses
     are lighter than the base on which they rest, he
     reasoned, they must float on the substratum of
(20) igneous rock, known as sima, as ice floes float on
     the sea. Then why, he asked, might continents not
     be subject to drifting? The rotation of the globe
     and other forces, he thought, had caused the
     cracking and, finally, the breaking apart of the
(25) original Pangea, along an extensive line repre-
     sented today by the longitudinal submerged
     mountain range in the center of the Atlantic.
     While Africa seems to have remained static, the
     Americas apparently drifted toward the west until
(30) they reached their present position after more than
     100 million years. Although the phenomenon
     seems fantastic, accustomed as we are to the con-
     cept of the rigidity and immobility of the conti-
     nents, on the basis of the distance that separates
(35) them it is possible to calculate that the continental
     drift would have been no greater than two inches
     per year.
The primary purpose of the passage is to
选项 A、describe the relative speed of continental movement
B、predict the future configuration of the continents
C、refute a radical theory postulating continental movement
D、describe the reasoning behind a geological theory
E、explain how to calculate the continental drift per year
答案D
解析
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