Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.
(A) has been dated to be 3.47 billion years old and thus is
(B) has been dated at 3.47 billion years old and thus
(C) have been dated to be 3.47 billion years old and thus are
(D) have been dated as being 3.47 billion years
(E) have been dated at 3.47 billion years old and thus are
OG 里有个类似的句子，楼主可以体会下：Fossils of the arm of a sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on the Greater Antilles islands.
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发表于 2017-4-11 20:38:50
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发表于 2017-4-12 10:37:49
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