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。

PS：问49.987*9.879／0.253化简结果最接近哪一个？ 选项a.b.c忘记了，d是1700，e是1800

数学书60页32题，有多少小于20的正整数等于3的正倍数与4的正倍数只和，答案说10个，我怎么查都是11个

PS：一个数是两位数，这个数大于11，个位数和十位数加起来的和是质数，问这样的 数有多少个？

57)If m is a positive odd integer between 2 and 30, then m is divisible by how many different positive prime numbers? 1)m is not divisible by 3. 2)m is not divisible by 5. 条件1 我理解的是 M 只能2到30之间，那么就有5，7，11，13，17，19，23，29，这么多个prime numbers. 条件2 我理解的是 M 可以是 3，7，9，11，13，17，19，21，23，27，29 这些，21可以被3和7除， 我判断条件1完全可以，条件2 我不太确定

62)if d is the positive integer and f is the product of the first 30 positive integers what is the value of d? (1) 10d is a factor of f. (2) d > 6 这个题目说d 是一个正整数，f 是30！阶乘，d的值多少， 这个题应该怎么推理？

DS：说一个整数N，最大不超过50，把从1到N的所有数拉出来列一起，数字里出现4的数字有几个？ 条件1：这些数里出现0的个数是出现4的个数的数字少11； 条件2：说N这个数是某个prime number的平方

错选了D，麻烦老师分析一下这题的时态！

错选了最后一个，麻烦老师讲解一下！

老师麻烦讲解这道题 Making things even more difficult has been general market inactivity lately, if not paralysis, which has provided little in the way of pricing guidance. A has been general market inactivity lately, if not paralysis, which has provided B there is general market inactivity, if not paralysis, lately it has provided C general market inactivity, if not paralysis, has lately provided D lately, general market inactivity, if not paralysis, has provided E is that lately general market inactivity, if not paralysis, which provides

讲解～