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。

A选项D选项动作发出者分别是什么A为什么不对 这个题能帮忙分析一下吗

请数学老师解答一下 谢谢 答案是星期四十点 我只能算出星期四12点

老师，对于这题ABC的their还有DE的they.他们指代有没有问题呢，就近的话我可以理解成指代records吗The loan company announced it would soon lend money to borrowers with proven records of their not paying back their loans on time,collectively known as subprime lending market. A.of their not paying back their loans on time B.of not paying back their loans on time, a group C.of not paying back their loans on time,with such a group D.that they do not pay back their loans on time. E.that they do not pay back their loans on time,such a group

图片里的并列不是很明白，还得麻烦老师帮忙将一下谢谢，此外， 下面这and连接的并列，不考虑语义，前面是过去分词，后面是it+过去分词这种属于并列吗？brightened the Northern Lights and it possibly knocked

本题是og19、sc720题，答疑器搜不出来，有如下疑问，谢谢老师 ①A选项不太明白， ②so as to 有没有这种说法？ ③D选项的enough和so as to能连用吗 ④E选项的so much as to有这种说法吗

希望金老师回答，这个题D选项有两个because怎么翻译整个句子呢？

老师，我记得所有质数里面只有2一个质数吧？不过答案还是-2，对吧？

张老师您好，这篇文章这道题目我不是很理解。第一句话说some historians认为during世界大战，unions和African A的关系是strong alliance，结束以后就没有了；第二句话说other scholars认为这些unions（organizd labor)一直都在帮助AA，可是并没有提到他们两者在二战之中的关系，所以不太懂为什么选C？老师您能不能说一下您的解题思路以及我思维上的一些问题？谢谢！

老师 这道题目不会做，我不理解为什么有3个男生，3个男生的位置都可以变，所以应该A33*A33，答案是A22，不懂求解

老师，这种题目有重复的字母我经常会有点混淆，我一般用的方法就是6C1*5C2*3C3，就是假设一共有6个空位，字母a选一个位置，还剩5个位置给b选两个位置，请问这种思路对吗？还有答案里的思路，我旁边注释的思路对嘛？求老师指教这类题目好的解题方法，谢谢！