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。

语法题目，请指定王文静老师回答。 问题语法讲义-修饰-第十题-Psychiatrist题目，我感觉选项A.B都是一样的意思，而且2个选项都没有问题，不知道该如何取舍。谢谢

老师，这道题怎么解的？我自己的理解是，速度慢的机器有1到3台，把每台多出来的1小时加在一起除4，求得的平均值就是小数点后的数字。所以求的平均值最小是0.25不可能是0.2因此选项A，7.2是不可能的。但是不知道这道题是不是这么理解的。

老师，这题答案是D，但我觉得是C。题中说大于10小于100的整数，应该是89个，掉到过来98+9，个位数是7

20题我计算是95页，但是答案是B，99页，不知道怎么算出来的。

老师25题答案给的是30%.可是我怎么算都应该是40%呢？我算错了吗？应该怎么算？

老师这道题没明白是什么意思

老师，第12题我没明白是什么意思

这个是Tina 老师在语法课上讲的一道题，不知道为什么搜不出来。想问一下，正确答案B 选项中的begun为什么不是过去分词引导的状语从句修饰the autographed quilt? Tina 老师在课上讲的是：begun是就近修饰名词fad的，我就很迷茫。我一直记得您讲过过去分词和现在分词作状语是修饰不到SVO 的O 上的，那这个为什么例外呢?谢谢您!

One day 340 million shares of stocks were sold. Among them 3/4 are domestic stocks. Among all the stocks sold 3/5 belong to institutional transactions. What is the minimum number of domestic shares could be traded by private parties on that day? 想问下这道题怎么画图解决？

请陆旭老师回答第25题，没有思路