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  3. Human impacts on the natural environment during the later part of the Holocene (beginning about 4,000 years ago) complicate inve

Human impacts on the natural environment during the later part of the Holocene (beginning about 4,000 years ago) complicate inve

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问题 Human impacts on the natural environment during the later part of the Holocene (beginning about 4,000 years ago) complicate investigations into environmental change during the period because the signals produced by human- and climate-induced change are sometimes difficult to separate. For example, in the later Holocene, one indicator of increased aridity due to climate change is an increase in pollen from grasses, as forest gives way to grassland. Such a change in vegetation could alternatively be attributed to human impact in the form of agricultural development. Examples of such human impact from 4,000 years ago would be small-scale, however, since the broad ecosystem changes brought about by the widespread adoption of agricultural technologies occurred later.
According to the passage, which of the following is true regarding environmental changes 4,000 years ago?
选项 A、No localized increases in grass pollen were caused by agricultural development.
B、Increases in grass pollen were at least sometimes a reflection of an increase in aridity.
C、Wholesale ecosystem changes probably resulted from agricultural development.
D、Any small-scale changes occurring then would not be detectable now.
E、Environmental change helped induce the adoption of agricultural technologies.
答案B
解析 A．No localized increases in grass pollen were caused by agricultural development．没有任何的草花粉的增加是由农业发展导致的。
解析：该选项太极端。文章最后一句只是说4000年前人类的农业活动规模小，而不是根本没有农业活动。
B．Increases in grass pollen were at least sometimes a reflection of an increase in aridity．草花粉的增加至少在某些时候可以反映出干旱的增加。
解析：本选项对应第二句，正确。
C．Wholesale ecosystem changes probably resulted from agricultural development．大规模的生态系统变化有可能来自于农业发展。
解析：4000年前农业发展规模很小，不可能导致大规模生态变化。不选。
D．Any small-scale changes occurring then would not be detectable now．任何那时候的小规模变化现在都无法发现。
解析：文章没提到。不选。
E．Environmental change helped induce the adoption of agriculanal technologies．环境变化帮助引发了农业技术的采用。
解析：文章没提到。不选。
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本试题收录于： GRE VERBAL题库GRE分类
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