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。

原文说 课堂上课的不及格率低于网络上课的 说明课堂上课的学生成绩更好 根据相关性确定了ad 但是不懂为啥ad方向都和原文是反的 都说网络上课的成绩更好 我还找不出ad之间差别 自己理解题目错了嘛 ？

argument是因为费用大于利润所以广告没有为公司带来长远经济效益 b就是说尽管近期没有体现 但是他们成为royal以后是一个长期的投资 后来肯定是有好处的 d的意思是这个现象是一个自然的发展规律 但是我认为它不能说明这个广告不是没用的

嘻嘻我再问一道数学题！44题我算的x=550，y=11，不明白答案怎么算的c啊，请老师解答，谢谢！

第一题，请问为什么不选A呢，AB是怎么选出B的呢

我选D，正确E 读完5个选项，按逻辑members会比物种更好，剩下DE，觉得差别不大，但D更加直接精炼（感觉正确是E的话和追求效率完全违背了哇，哭）

？？我选C，正确选A AB一组，CDE一组 做错思路：首先看AB开头就有代词their觉得没法指代，内心已经差不多把他俩都排除了，往下看一点，看的比较急，没有彻底清楚句意和结构，就觉得两个逗号了还没有出现主语很奇怪，直接AB全部排除（读是读句意啊啊啊啊，就抓着结构不放是什么鬼，两个逗号是形容词并列修饰。。。）；CDE，对比发现最后都有代词，都会以指代不清，但只有C代词和指代对象相隔最近相对清楚，就选了。（其实看到这里既然都有指代不清为啥不重新看一下AB？？）（问题：代词指代放前面一定就指接下来紧接的名词吗？那么相对代词放在后面还要回头找对应指代，在所有选项都存在代词指代时，放前面是不是总是更好？）（from when…有这种用法吗？）

我选D，正确E AB一组，CDE一组 做错思路：速度的话用介词at 比with 好，CDE中选，对比than前后应该一致，前面既然是速度，后面我认为也应该是名词结构才能并列，所以不应该有is/are（难道说正确选项E是than后省略speeds＋定语连接词which？）

答案是E，面授课记的是A，我选的C。。。啥情况。。。 思路：依靠单复数剩ACE，最后时态差别，去前文找发现都是过去式，排除E，纠结，原文有by所以考虑是不是被动就选了C。

后面应该是完整句子排除C，B指代不清排除，ADE最明显区别就是时态，认为是动作导致activate所以应该是单数，排除D，觉得A比E舒服，错选A。

选了B，正确是 D 读了A觉得SO THAT不对，然后读B觉得逻辑才对（这时其实我应该用这个点去排除就只剩下BD），但我顺着读了，然后排除了C，看到DE都有will，但是原文后面已经有专家正在alarm了，按照句意逻辑我认为不应该还未实行，直接就排除了。