According to a theory advanced by researcher Paul Martin，the wave of species extinctions that occurred in North America about 11,000 years ago，at the end of the Pleistocene era，can be directly attributed to the arrival of humans，i.e.，the Paleoindians， who were ancestors of modern Native Americans. However，anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demonstrate that Paleoindians hunted them.Nor were extinctions confined to large animals： small animals，plants，and insects disappeared，presumably not all through human consumption. Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene. Still，Krech attributes secondary if not primary responsibility for the extinctions to the Paleoindians，arguing that humans have produced local extinctions elsewhere.But，according to historian Richard White，even the attribution of secondary responsibility may not be supported by the evidence. White observes that Martin's thesis depends on coinciding dates for the arrival of humans and the decline of large animal species，and Krech，though aware that the dates are controversial，does not challenge them；yet recent archaeological discoveries are providing evidence that the date of human arrival was much earlier than 11,000 years ago. 　3. In the last sentence of the passage， the author refers to “recent archaeological discoveries” (lines 27-30) most probably in order to 　　(A) Refute White's suggestion that neither Martin nor Krech adequately account for Paleoindians' contributions to the Pleistocene extinctions 　　(B) Cast doubt on the possibility that a more definitive theory regarding the causes of the Pleistocene extinctions may be forthcoming 　　(C) Suggest that Martin's， Krech's， and White's theories regarding the Pleistocene extinctions are all open to question 　　(D) Call attention to the most controversial aspect of all the current theories regarding the Pleistocene extinctions 　　(E) Provide support for White's questioning of both Martin's and Krech's positions regarding the role of Paleoindians in the Pleistocene extinctions 老师，我在做这道题的时候，首先定位到最后一句觉得没说什么重点，就有个yet转折，可能这是用来驳斥前面的某些观点的。所以看选项找有没有驳斥的意思的， 发现5个选项全都在驳斥。。。心里慌了往前找。再回去找的时候时间已到。我就随便选了个B（时间一到各种混乱），因为在做这篇文章之前，我大体看了下原文，记住了原文讲的是P反驳M，W反驳P。后来答案我也看明白了，我认为我做这道题的思路出现了偏差，我想问一下应该怎么修正。

2

as, since和when的用法区别

看不懂，错选C

正确选项E取非怎么理解（我后来直接加强倒是想懂了）

如何解这两道题呢？

What is the median number of employees assigned per project for the projects at Company Z? 1, 25 percent of the projects at Company Z have 4 or more employees assigned to each project. 2,35 percent of the projects at Companny Z have 2 or fewer employees assigned to each project.

18！能被6整出，但不能被6的N+1次方整除，问n是多少？ 解释说求的18！有8个6的因子，哪八个阿？

原文我读到：不诚实就难达成政治compromise，结论是不诚实可以说明运作良好。 最后我剩下了A和C两个选项，A的意思是“达成Compromise不一定说明运作良好”；C的意思是“选民有其他判断标准”。 当时我的反应是“C中说到选民，跟原文意思关系较近”。 想听听老师的解题思路，以及我思路的问题。 谢谢老师。

原文 我是这么理解的 想让我解释为什么水藻擅长在慢流速水生长但是却在极度干旱的情况下（非常慢的水流速） 死翘翘 。 我觉得ABCDE 都无法解释 这个现象。。 D选项在说 什么在澳大利亚会经历一个完全的干旱然后又恢复。我感觉跟没说一样啊。 不知道是如何解释原文的 还希望老师解答 ^.^