编辑点评: GRE阅读考试的材料,非常强调逻辑的关系,所以逻辑要点是大家在解GRE阅读题的时候的关键,本文就为大家例举了这样一篇逻辑短文,供大家参考和练习。
随着GRE阅读考试的难度日益增加,大家需要有针对性地进行练习,本文为大家例举的就是逻辑短文的练习,文末还附有答案,供大家更好地练习。
The deep sea typically has a sparse fauna dominated by tiny worms and crustaceans, with an even sparser distribution of larger animals. However, near hydrothermal vents, areas of the ocean where warm water 5 emerges from subterranean sources, live remarkable densities of huge clams, blind crabs, and fish.
Most deep-sea faunas rely for food on particulate matter,ultimately derived from photosynthesis, falling from above. The food supplies necessary to sustain the 10 large vent communities, however, must be many times the ordinary fallout. The first reports describing vent faunas proposed two possible sources of nutrition: bacterial chemosynthesis, production of food by bacteria using energy derived from chemical changes, and 15 advection, the drifting of food materials from surrounding regions. Later, evidence in support of the idea of intense local chemosynthesis was accumulated: hydrogen sulfide was found in vent water; many vent-site bacteria were found to be capable of chemosynthesis; and extremely 20 large concentrations of bacteria were found in samples of vent water thought to be pure. This final observation seemed decisive. If such astonishing concentrations of bacteria were typical of vent outflow, then food within the vent would dwarf any contribution from advection. 25 Hence, the widely quoted conclusion was reached hat bacterial chemosynthesis provides the foundation for hydrothermal-vent food chains an exciting prospect because no other communities on Earth are independent of photosynthesis.
【新GRE逻辑阅读 每日一练27】相关文章:
最新
2016-03-01
2016-03-01
2016-03-01
2016-03-01
2016-03-01
2016-03-01