Ron的解释
A选项中的being: "being" doesn't make sense because it's not parallel to anything in the earlier part of the construction.
B:the real problem is that "is" has no parallel in the first part of the comparison - i.e., the first part doesn't say "is emitted" or "are emitted" - and so the comparison is wrong.
果因:
果: the camp probably dates to no later than 1630,
因:since no European trade goods were found at the site, and European traders were active in the region from the 1620's onward.
B取反削弱? 那A呢?为什么不对?
Over the last 150 years, large stretches of salmon habitat have been eliminated by human activity: mining, livestock grazing, timber harvesting, and agriculture as well as recreational and urban development.
Low levels of straying are crucial, since the process provides a source of novel genes and a mechanism by which a location can be repopulates should the fish there disappear.
Ron的解释
A选项中的being: "being" doesn't make sense because it's not parallel to anything in the earlier part of the construction.
B:the real problem is that "is" has no parallel in the first part of the comparison - i.e., the first part doesn't say "is emitted" or "are emitted" - and so the comparison is wrong.
感恩