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TPO托福阅读真题答案及解析：托福阅读文段的结构和出题点都有一定的规律，比如说托福阅读文段一般是总分总的格式，考生重点关注首段，尾段，转折 句，开头句，基本上就能找到主题句，从这个方面来说，练习托福阅读真题，从中总结托福阅读考试经验是十分必要的，下面新东方网为大家整理一份TPO托福 阅读真题答案及解析，希望对大家有所帮助。 托福阅读真题： The Long-Term Stability of Ecosystems Plant communities assemble themselves flexibly, and their particular structure depends on the specific history of the area. Ecologists use the term succession to refer to the changes that happen in plant communities and ecosystems over time. The first community in a succession is called a pioneer community, while the long-lived community at the end of succession is called a climax community. Pioneer and successional plant communities are said to change over periods from 1 to 500 years. These changesin plant numbers and the mix of speciesare cumulative. Climax communities themselves change but over periods of time greater than about 500 years. An ecologist who studies a pond today may well find it relatively unchanged in a years time. Individual fish may be replaced, but the number of fish will tend to be the same from one year to the next. We can say that the properties of an ecosystem are more stable than the individual organisms that compose the ecosystem. | 
