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。

The profit from the sale of a certain appliance increases, though not proportionally, with the number of units sold. Did the profit exceed $4 million on sales of 380,000 units? (1)The profit exceeded $2 million on sales of 200,000 units. (2)The profit exceeded $5 million on sales of 350,000 units. 1不够，2 怎么看？ 谢谢

A report consisting of 2,600 words is divided into 23 paragraphs. A 2-paragraph preface is then added to the report. Is the average (arithmetic mean) number of words per paragraph for all 25 paragraphs less than 120 ? (1) Each paragraph of the preface has more than 100 words. (2) Each paragraph of the preface has fewer than 150 words.

PS ：给树标号，范围是201到740 某一品种的树的百位一定是4、5、6、7，个位一定是2、3、4、5， 求随便抽一棵树不是这个特定品种的树的概率？

DS：is|x-y|>|x-z|？ 条件1：是y的绝对值大于z的绝对值 。 条件2：是x<0。

1 3 2 B 3 4 4 10 A 2 8 1 第一列是调查的信用卡的拥有数，第二列是对应的人数，如第一行的意思就是三个人每人拥有一张信用卡，问信用卡拥有数的中位数？ （1）A=6 （2）B=7

m*(m+5)*(m+6)的因数可能是哪几个？ 3 ， 4 ， 6

连续四天股票收盘分别停在了8230，8390，8460，8530（数字可能有出入），第五天收盘多少？ （1）这组数的差值是220 （2）8390是这组数的中位数

三角形ABC，点D在AC上，D不能与AC相交（解释说这句话的意思是BD不能等于BA和BC，是独立的），AB是否等于BC？ （1）角BDC=角BCD （2）BD=DC

有A和B，共n个人（人数已知）他们每个人都可以同意或不同意一件事情，已知A有X人，B有Y人，bothA和B有Z人，求又是B又不同意的人？

给了两种书数量的比例3：X，求X？ （1）数的总数是15 （2）X小于13 讨论说选A，因为比例不能是3:12，必须要是最简形式1：4，可是我觉得3:12可以，3:2也可以，条件1不充分