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。

请问这道题c选项为什么不能用过去完成式？之前的“had installed”不也是过去完成式吗...怎么判断什么时候用过去完成时什么时候用现在完成时什么时间用一般过去时啊？

请问这道题e选项“that”表示了什么？

请问在这道题里面 to do和doing的区别是什么？

请问这道题为什么不可以用过去完成时？“its trunk”里面的its会不会被当成是aquatic animal而不是大象？“with”之后是不可以接整句吗？

请问这道题b、c为什么不对

请问这道题e选项错在哪里？

请问这道题为什么不能选e？

请问为什么c不对？that of是什么意思？

请问in which 和 where的区别是什么？哪个能指代抽象地点，哪个是实际地点？

D选项错的原因之一是说不应该用that they participate 请问这个错在哪里了？