In the country of Veltria, the past two years' broad economic recession has included a business downturn in the clothing trade, where sales are down by about 7 percent as compared to two years ago. Clothing wholesalers have found, however, that the proportion of credit extended to retailers that was paid off on time fell sharply in the first year of the recession but returned to its prerecession level in the second year. Which of the following, if true, most helps to explain the change between the first and the second year of the recession in the proportion of credit not paid off on time? (A) The total amount of credit extended to retailers by clothing wholesalers increased between the first year of the recession and the second year. (B) Between the first and second years of the recession, clothing retailers in Veltria saw many of their costs, rent and utilities in particular, increase. (C) Of the considerable number of clothing retailers in Veltria who were having financial difficulties before the start of the recession, virtually all were forced to go out of business during its first year. (D) Clothing retailers in Veltria attempted to stimulate sales in the second year of the recession by discounting merchandise. (E) Relatively recession-proof segments of the clothing trade, such as work clothes, did not suffer any decrease in sales during the first year of the recession. 这道题错选了A。 思路如下： 题目问的是为什么在经济不好，衣服卖不动的情况下，第一年零售商还不上钱第二年就能还上了。讲的是零售商还钱的问题。 当时留下的是A,C,D 排除D是因为觉得，即使刺激销售量衣服打折也不能说明能还上钱。可能打折卖1块，纵使家当全卖了也不够。 排除C是因为觉得， 那些本身经济状况就很差的在第一年被淘汰掉以后，剩下的那些没说经济状况如何啊，如果也不咋地，第二年还是得淘汰啊。 A选项当时觉得，即使credit extended，对pay off on time也无太大用处，但最起码跟原文意思接近。所以选了A。

如果n是19的话n+1才是20。那a20不是应该等于a19+19吗，为什么会加20呢？条件二给的公式不是说a(n+1)=a(n)+n吗？我算的是1+2+...+19+19这样

@陆旭老师 第39题要怎么做呢？

@唐小梅老师 这道题用您的方法咋做呀？

@英吉老师 第715题的b选项为啥不算说了原文解释的对立面。是不是因为它主要讲的是electricity不是fossil fuel？ e选项这个地方算是要知道的常识吗？因为当时排除掉e选项就是因为自己脑袋里根本没有这个概念，感觉与原文无关。但是一旦听你说了，接受了说这个设定我是能理解的。所以以后再碰到这种不确定的情况，就默认判定这个选项是可行的，然后再去结合文章看是否支持原文逻辑链吗？

@陆旭老师 当出现overlapping info时，应该用matrix比较好还是用韦恩图比较好？

@英吉老师 如果这道题选了a，算是犯了什么错误？

请问老师这道题是不是答案给错了？不应该是4+8+12+...+200求和吗

想问一下小梅老师这道题的思路

想问一下小梅老师这道题如何快速得出答案？感觉自己解题思路有问题 2分钟内无法解答 类似题有没有什么快速切入的技巧？

A为什么不行？