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。

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。

求问此题：DS：一个矩形地毯问面积是否大于160？ 条件1：对角线>21 条件2：至少有一条边大于8 谢谢！

求问此题的详细解法。谢谢老师~！

下面那个圆的半径我求不出来。请老师答疑！谢谢！

请问这道题是选E吗（答案我给忘了）？一个数N是否能被4！的三次方整除 1）这个数能被6！的二次方整除 2）这个数能被9！整除

5^500 + 5^501 + 5^502 + 5^503 最大的质因子是多少？求具体解法！谢谢老师！

求问此题：一个正方体，选三条不在同一顶点的棱涂成红色，问有几种方法？我的计算过程是C(12,1)*C(7,1)*C(2,1)=168.不知道思路正确与否，请老师答疑解惑。谢谢！

此题求解：DS：3个数，问中位数是否大于平均数？ 条件1：最大数和最小数之和大于中位数； 条件2：最大数=450+平均数，最小数=平均数-150 谢谢！

一个正方体，选三条不在同一顶点的棱涂成q红色，问有几种方法？ 请may回答 我算的是（ C3 12 ）-8