【meaning】
the problem with (a) is that it says only that companies are aware "that there ARE connotations". but the companies don't necessarily know what those connotations are.
//
i am aware that discounts are available this weekend.
--> i know that there ARE discounts, but i don't necessarily know the specifics.
i am aware of the discounts available this weekend.
--> i actually know the specifics (percentages or whatever) of the discounts.
Moreover, whereas P. ochraceus occupies an unambiguous keystone role on wave-exposed rocky headlands, in more wave-sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels.
A declining population should not be confused with an endangered one
没有仔细读所有选项导致误选c
An endangered population is always rare, almost always small, and, by definition, under constant threat of extinction even without a proximate cause in human activities仔细读文章，c错误，constant
直觉
They do not clearly constitute evidence of general environmental degradation. 对
第二段最后一句Anecdotal reports of population decreases cannot distinguish among these possibilities, and some amphibian populations have shown strong fluctuations in the past.
They have probably been caused by a combination of chance events. 错 ，作者没这么说
earlist 时间相关
Though the extreme rapidity of quantum tunneling was noted as early as 1932, not until 1955 was it hypothesized—by Wigner and Eisenbud—that tunneling particles sometimes travel faster than light.
只有这句话涉及时间，1932年认为not travel faster than light.
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a中没有提到region这一项
frame of reference 参照系