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。

请问数学老师 条件2为什么成立 谢谢老师

老师您好，这道阅读理解不会做，用定位的方法读了原文也没太懂为什么选D

文章的最后一句话回答了这个问题，也就是C选项，我不懂为什么正确答案是B

ken老师你好，这道题目我的思路是设97、98、99依次为a、b、c，根据题目得出b=C+y; b=a+x。条件1）x>y，可以得出a<c。 第二个条件不太懂。而且这道题目的开始的的less、 more in 1999，这些术语我转化成公式就浪费了半个小时，想问老师有没有更高效的解决办法？

请数学老师讲解下思路

麻烦老师给我讲解一下这一题，通过The body…was that of the man ，身体是那个男人的一部分，而不是身体是那个男人。这个点排除ABC. DE关于时态部分不是很清晰

请数学老师解答下第三个为什么不行

请数学老师帮我解答下，再讲下怎么画图 谢谢老师

麻烦老师给我辨析一下图1和图2，关于图1那题当时选错之后机构老师给我解答的是40 to 44 million years 是一个时间区间，不能用estimate at 因为 at 有精确到某个点的意味。那么图2的正确答案是不是因为3.47 billion years 是一个精确的年份所以要用 at 。。

麻烦老师给我解答一下这题，这题BUT后面主要想表达的核心语意是 家庭用电少于百分之一和家里面的电仍然是由蜡烛提供。我觉得B 顺着读下去也能表达这个语意，就是 我觉得AB 都能表达这个语意，关于两者的差异我不是很清晰 麻烦老师帮我辨析一下