7篇阅读里的一题求助
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 that 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 vegetation 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.2. According to the passage, which of the following is true regarding environmental changes 4,000
years ago?
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.
最后一句我没太读懂，说这些人类的影响只是很小的范围，因为大的被农业的广泛开发而引起生态系统改变在后面发生。
不知道这样理解对不对。
如果是这样领结的话，那么我觉得应该选C才对。
答案是B。
B在原文里是For example, in the later Holocene, one indicator of increased aridity due to climate change is an increase in pollen from grasses
一个由气候变化引起的干旱增加的标志是pollen from grass
那么就是干旱是pollen from grass 的indicator 或者说reflection，这也能说的通。 问的是四千年前，当时人类活动（如agricultural development）产生的影响是非常小的，也即相对于气候变化引起的环境变化是可以忽略不计的。然而C 对环境变化加了wholesale这个定语，但既然已知当时人类活动的影响是可以忽略不计的，所以C不正确。
B和C表达的意思相反，是对的。
根据文章最后一句话可知：4000年前人类的农业活动是small-scaled，因此无法带来broad ecosystem changes, 侧面的说明了4000年前的increased aridity是因为气候原因导致的increase in pollen from grass，而不是人类导致的。选B正确
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