According to the passage, human activity has had which of the following effects on salmon populations?
A [url=]An increase in the size of salmon populations in some previously polluted rivers[/url]
B [url=]A decline in the number of salmon in some rivers[/url]
C [url=]A decrease in the number straying salmon in some rivers[/url]
D [url=]A decrease in the gene flow between salmon populations that spawn in polluted streams and populations that spawn in pristine streams[/url]
E [url=]A decline in the vulnerability of some salmon populations to the effects of naturally occurring habitat destruction[/url]
答案B,可是D有什么不对么?
翻了以前的讨论,但是没有第11题,谢谢各位!!
作者: hanlei84921 时间: 2011-8-4 20:20
原文关于Gene Flow这么说的Such a dra-matic increase in straying from damaged areas to more pristine streams results in substantial gene flow, ... 意思是什么情况下导致了Gene Flow
而D是说derease in the Gene Flow between A and B,有两处明显错误
我觉得D肯定是错的吧~宁可是increase也不是decrease啊~the rate of spraying increased so more salmon spawn in pollute stream instead of pristine stream and the gene flow should be increased~不知道对不对作者: clairesslc 时间: 2011-8-8 06:31
Bis correct because more salmon find alternative stream so that the amount ofsalmon in some rivers declined naturally.
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