2021年托福阅读PASSAGE 88
试题及答案
PASSAGE 88
Generally, in order to be prerved in the fossil record, organisms must posss hard body parts such as shells or bones. Soft, fleshy structures are quickly destroyed by predators or decayed by bacteria. Even hard parts left on the surface for a certain length of time will be destroyed.
应急预案演练记录
Therefore, organisms must be buried rapidly to escape destruction by the elements and to be 容仪protected against agents of weathering and erosion. Marine organisms thus are better candidates for fossilization than tho living on the land becau the ocean is typically the site of dimentation, whereas the land is largely the site of erosion.
The beds of ancient lakes were also excellent sites for rapid burial of skeletal remains of freshwater organisms and skeletons of other animals, including tho of early humans. Anci
ent swamps were particularly plentiful with prolific growths of vegetation, which fossilized in abundance. Many animals became trapped in bogs overgrown by vegetation. The environment of the swamps kept bacterial decay to a minimum, which greatly aided in the prervation of plants and animals. The rapidly accumulating diments in flood plains, deltas, and stream channels buried freshwater organisms, along with other plants and animals that happened to fall into the water.
Only a small fraction of all the organisms that have ever lived are prerved as fossils.
Normally, the remains of a plant or animal are completely destroyed through predation and decay. Although it ems that fossilization is common for some organisms, for others it is almost impossible. For the most part, the remains of organisms are recycled in the earth, which is fortunate becau otherwi soil and water would soon become depleted of esntial nutrients. Also,most of the fossils expod on Earth's surface are destroyed by weathering process. This makes for an
incomplete fossil record with poor or no reprentation of certain species.
The best fossils are tho compod of unaltered remains. Generally, it is the inorganic hard parts, compod mostly of calcium carbonate, that form the vast majority of unaltered fossils.
Calcite and aragonite also contributed to a substantial number of fossils of certain organisms.
1. According to the passage , an organism without hard body parts
(A) is not likely to appear in the fossil record
(B) is not heavy enough to sink below the surface
(C) is not attractive to predators
(D) takes a long time to decay
2. The word "agents" in line 5 is clost in meaning to
(A) dangers
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(B) examples
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信息验证码(C) areas
(D) caus
3. Why are marine organisms good candidates for fossilization?
应接不暇的意思(A) They have more fleshy structures than land organisms.
(B) It is likely that they will be buried rapidly.
(C) The water environment speeds the decay caud by bacteria.
夜吧(D) It takes longer for them to be prerved.
4. The fact that the "land is largely the site of erosion" (line 7 - 8) is significant becau
(A) erosion is less destructive than dimentation.
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