扫描二维码，直接登录
题库 / Prep2012-SC-64
Although beavers can still be found throughout the western United States, their number has declined compared with the eighteenth century, when the abundance of beavers lured armies of European trappers into the Rocky Mountain region to slaughter them for their pelts.
their number has declined compared with
their numbers have declined compared with
their numbers have declined since
their numbers have in comparison to those of
the number of them declined since
题目分析：
在(A)(B)(D)中，their number has declined和the eighteenth century之间是对比关系（compared with）；在(C)(E)中，their number has declined和the eighteenth century之间是自从关系（since）。在逻辑上，与划线部分形成转折关系（although）的内容是：“在美国的西部海狸依然能被发现（beavers can still be found throughout the western United States）”，如果想和前文形成转折关系，那么划线部分的内容应该表述为“海狸的数量自从18世纪就开始下降了”而不是“相比于18世纪海狸的数量，现在海狸的数量下降了”（如果仅仅是数量下降话，这反而证明海狸应该能被发现（只是下降，没有消失），两个小句不会存在转折关系），可以排除(A)(B)(D)。第二，如果时间状语是由since引导，那么谓语动词必须以完成时的形式出现，可以排除(E)，答案为(C)。
选项分析：
略
numbers是因为beavers有很多种，所以是复数？
同问啊。这里Number不应该单数才对吗
numbers表示可以被具体化的几个数。如果明确知道有多少数量，用numbers.语法和逻辑上都木有问题呀~
我也是把numbers都排除了
网上找到的解释： The singular number is non-idiomatic and does not capture the reality that at different points between the eighteenth century and now, different numbers have described the beaver population in western U.S."
登录 或 注册 后可以参加讨论
我理解A,B,D选项应该是主从句顺序的问题（图形背景原则）。正确顺序是 Although numbers declined compared with 18th century, they can still be found throughout thw western US.
这道题目的五个选项都是一样的主从句顺序呀~
A、B、D选项比较的对象是“the number has declined”和"18th century",但是数量下降这件事情和一个时间节点不是等同的地位，不能这么比较
登录 或 注册 后可以参加讨论