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。

请唐塘老师分析一下这道题，谢谢

想问下may老师什么时候变化率的计算公式 什么时候分母是被减数，什么时候是减数 像这题求时间的变化率分母是距离也就是被减数，但是对于其他年增长之类变化率的分母就是减数，想知道这个区别，谢谢老师

请文静老师解答：老师我读主旨大概总结为：各个政府开出优惠政策来吸引商家只会两败俱伤，这样不会创造更多的就业岗位，只会影响工作的布局。觉得B很核心的反应了文章主旨。因为从文章主旨上读出这样的行为各个政府都不受益只是影响工作布局罢了，那为什么政府还要重点关注E里竞争者开的条件呢？

老师您在讲课的时候把总数设为了a,将有副作用设为y,将有疗效设为了x,那通过条件（1）就可以知道有疗效为0.9a,没有疗效为0.1a,但是是怎么得出“没疗效有副作用”也为0.1a从而结合题设把y用a的式子表示的呢？感觉只能得出T这一栏里“没有疗效”的总数为0.1a哇

想问下may老师这题怎么做

想问下may老师怎么做

想问下may老师怎么做

[急] 这题七龙珠答案给的C，但是这里的contemporary只能是形容词或者名词，是不是不能直接接在名词后面用？如果这是个硬伤的话，E会不会更好一些呢？

[急] 请问May老师，这里通过连接下面圆的圆心，是不是是不是可以得到r跟b的直接关系，这样选A是不是就可以了呢？

当时老师讲的答案是A。statement 1 sufficient；statement 2 not sufficient。但是我现在不太理解了，觉得答案有些问题，能不能再详细的讲一下这道题怎么做？谢谢！