TOEFL Listening: TPO-TOEFL阅读TPO - X471MS2Z_G0IN5P5N$

The remains of ancient life are amazingly well preserved in the form of fossils. A. Environmental characteristics like those present on ocean floors increase the likelihood that plant and animal fossils will occur. B. Fossils are more likely to be preserved in shale deposits than in deposits of clay and silt. C. The shells of organisms can be preserved by processes of chemical precipitation or mineral exchange. D. Freezing enables the soft parts of organisms to survive longer than the hard parts. E. Comparatively few fossils are found in the terrestrial deposits of streams and lakes. F. Thin films of carbon may remain as an indication of soft tissue or actual tissue may be preserved if exposure to bacteria is limited.