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科學(xué)家根據(jù)那些化石的骨骼結(jié)構(gòu)確定其年代.Scientists have dated the fossils by their bone structure.有兩個因素對生物化石的保存是有利的.Tow factors are favorable for the preservation of organisms as fossils.它們是怎樣變成化石的?How did they become fossils?...

“化石的”的英語可以翻譯為：fossil ...