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来源:雅诚德英语网
Occasionally , a sequence of fossil-rich layers of rock permits a comprehensive look at one type of organism over a long period of time.
偶尔,一个富含化石的岩层序列可以让我们持续并全面地观察一种生物。
Occasionally , a sequence of fossil-rich layers of rock permits a comprehensive look at one type of organism over a long period of time.
偶尔,一个富含化石的岩层序列可以让我们持续并全面地观察一种生物。