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。

DS：如果x和y是≥0的数，问3^xy次方是多少？ 条件1：5^x=11^y 条件2：3^x=9^y 请问这题答案是B吗？谢谢老师！

不明白这道题的总体积为什么是（x+2）(y+2)(z+2)而不是（x+1）(y+1)(z+1);厚度不是1吗？谢谢！

我觉得这题答案应该是A吧？∵105拆分质因数可得105=3*5*7（3个完全不同的质因数）∴x+y+z=15。怎么会是C呢？？？？

向May提问，我觉得这题情况会分得很复杂，想听下老师的思路？

想向May老师提问。这题我知道条件1单独成立，但对条件2没什么思路，只能想到穷举法，当p等于2*5,3*5,3*5,2*3,2*5,3*5时，m等于2*3,2*3,2*5,5,3,2，然后一个个除发现有的余数是1，有的余数大于1，条件2单独不成立。想问老师这个思路对吗？有没有更加简洁的思路？

不懂此题。已知有A,B,C和D共4个人；问：现在从这四个人中选出3人，是ACD的概率是多少？请详细解释，谢谢老师！

不理解第一个条件均值如何得出关于6倍数的结论，是连续7个数除7余数为5则为6的倍数，所以有一个6的倍数？

不理解第一个条件均值如何得出关于6倍数的结论，是连续7个数除7余数为5则为6的倍数，所以有一个6的倍数？

第8题的思路是以BC为底，从F向BC做垂线，跟BC交点H，FH为三角形FBC的高。然后三角形BFH跟三角形BDC相似，h：30=BF：BD，但是BF长度未知，望老师解答。

第8题的思路是以BC为底，从F向BC做垂线，跟BC交点H，FH为三角形FBC的高。然后三角形BFH跟三角形BDC相似，h：30=BF：BD，但是BF长度未知，望老师解答。