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。

老师例5，7的平方49，没有超过100啊，为什么不能选？

老师，这道题你换了好几次思路，真的没听懂！谢谢！

老师这道题没懂，我也不会拆分！

老师这个是怎么解出来的？拆分？这么大的数不会拆哦

老师，这里不懂条件1怎么算出来的， 40怎么来的？谢谢！

PS：|nx-8|≤4，有多少个整数n使得恰好只有2个整数解x？ 求问may老师

老师，这里看不懂二分之Q减一是什么？

老师例7的A怎么能成立呢？把2带进去，一个方程俩未知数啊？

讨论的71那三个情况不是3的倍数？70那俩是三的倍数？213能被三整除啊，其他不能整除怎么70那些都是3的倍数呢？谢谢哦！

我觉得这道题应该选E，因为当ab同时大于1，原命题成立，当ab同时大于0小于1，原命题不成立