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。

数学：请问老师这道排列组合怎么解 感觉好复杂

老师，请问这道题思路是什么？

老师，求该题解题思路

DS：说一个女生有一些 tax deductible 其中捐给 b 让她少交了 210 的税，问什么忘记 了求补充，好像是她总收入是多少？ 条件 1：给了税率是 28% 条件 2：给了可税工资（income-deductible）是个五位数。 income*0.28-（income-deductible）*0.28=210 构筑纠结很久 因为题里面说捐给 b 只是 deductible 其中一项，还有其他未知，所以最 后选了 e，现在感觉选 c 请问陆老师，应该选什么？谢谢！

DS：n 是三个不同质数的积，这些质数都在 1-15 之间，问 n 是否＜700？ 其中一个条件是 n 与 70 没有公约数 【补充】 DS：x,y,z 是三个质数，xyz<700？ 条件 1：三个数不大于 14 条件 2：三个数里面有 70 的因数 s 轩辕十四 12/20 【122-补充】 DS：三个整数，问他们的积和一个常数的关系 条件 1：都是小于 15 的质数 条件 2：是 30 的 factor 构筑：这个好像也是个变体吧，好迷啊 ggggggbbbbbb bb 12/20 【122-补充】 DS：Integer p: is p>700? 条件 1：p is product of three prime numbers from 1-15 条件 2：p has no common factor with 70 请问陆老师，这道题选什么？谢谢！

DS：2x^2+bx+8=0，只有一个实数根，求那个字母的值？ 条件 1：b<0 条件 2：lxl>5 x的绝对值 请问陆老师，这道题选什么？谢谢

想请教一下陆老师，我觉得这道题应该是用相似三角形做，看了图觉得应该是用角1和角2相等来证明。但是由题干给的条件，我不知道如何得出角1和角2相等

请问老师图里的这道语法比较，不太明白，如何区分到底比较的是什么呢？谢谢

请问May, 我这道题不知道怎样做？谢谢！

请问May老师，请问这题选5 吗？