The author mentions the "aftermath of the Mount Saint Helens eruption" most likely in order to
A provide an example of the process that allows the repopulation of rivers whose indigenous salmon population has become extinct
B indicate the extent to which the disturbance of salmon habitat by human activity in one stream might affect the genetic structure of salmon populations elsewhere
C provide a standard of comparison against which the impact of human activity on the gene flow among salmon populations should be measured
D show how salmons' homing instinct can be impaired as a result of severe environmental degradation of their natal streams
E show why straying rates in salmon populations remain generally low except when spawning streams suffer severe environmental disturbance
其中的C选项的which指代什么啊？怎么翻译啊
麻烦大牛指点一下啊
作者: Elfy 时间: 2013-6-18 16:46
impact of human activity 的影响可以通过aftermath of the Mount Saint Helens eruption的数据来衡量作者: kevinjpcn 时间: 2013-6-18 17:49
Elfy，谢谢。
我明白了。
measure against是个习惯用语，表示以...来测量。
句中的against which 的which指代standard，也就是measure against a standard of comparison
也就是aftermath of the Mount Saint Helens eruption作为了一个比较的标准（a standard of comparison)。我以前认为which指代comparison所以没有理解这个句子，其实comparison跟在介词of的后面，不能被which指代的啊。
举例：
What star serves as a standard of comparison against which the brightness of other star is measured?
http://wiki.answers.com/Q/What_star_serves_as_a_standard_of_comparison_against_which_the_brightness_of_other_star_is_measured 作者: 断了的弦 时间: 2019-12-14 23:18
should be measured 的主语是什么啊？这是一句虚拟语气吗？