跪求一道逻辑题的解释，谢谢

xw909

In recent years the climate has been generally cool in northern Asia. But during periods when the average daily temperature and humidity in northern Asia were slightly higher than their normal levels the yields of most crops grown there increased significantly. In the next century, the increased average daily temperature and humidity attained during those periods are expected to become the norm. Yet scientists predict that the yearly yields of most of the region's crops will decrease during the next century.

Which one of the following, if true, most helps to resolve the apparent paradox in the information above?

(A) Crop yields in southern Asia are expected to remain constant even after the average daily temperature and humidity there increase from recent levels.

(B) Any increases in temperature and humidity would be accompanied by higher levels of atmospheric carbon dioxide, which is vital to plant respiration.

(C) The climate in northern Asia has generally been too cool and dry in recent years for populations of many crop insect pests to become established.

(D) In many parts of Asia, the increased annual precipitation that would result from warmer and wetter climates would cause most edible plant species to flourish.

(E) The recent climate of northern Asia prevents many crops from being farmed there during the winter.
这道题选什么，为什么？
答案给的是c
但是我感觉如果气温升高，虫子多了，为什么近几年，庄稼还会增加呢，虽然这么想有点歪，但是就是想不通，为什么近年来庄稼会增长
谢谢

kenhu

第一句话就是解题的关键，寻找差异性，最近几年的庄稼产量增加的原因就是寒冷气候使得害虫不能生存，下一个century如果没有寒冷气候，那么害虫增加，产量下降，C很好论证了这点。

xw909

第一句话就是解题的关键，寻找差异性，最近几年的庄稼产量增加的原因就是寒冷气候使得害虫不能生存，下一个century如果没有寒冷气候，那么害虫增加，产量下降，C很好论证了这点。

-- by 会员 kenhu (2010/7/5 12:07:24)

那对么？你的意思是气温升高了，虫子多了，庄家还增长了？这不矛盾么？

xw909

第一句话就是解题的关键，寻找差异性，最近几年的庄稼产量增加的原因就是寒冷气候使得害虫不能生存，下一个century如果没有寒冷气候，那么害虫增加，产量下降，C很好论证了这点。

-- by 会员 kenhu (2010/7/5 12:07:24)

一直很冷，虫子生长的不好，突然有一阵子，天气暖和，湿润了，虫子增长吗？如果增长了，就矛盾了，庄家不能也跟着增长吧，如果不增长，就不能选c了啊

kenhu

题目有好几个时间概念，“In recent years .”指的是最近几年气候通常较冷。“But during periods ”指的是最近在一些时期气候和湿度比较高的时候粮食产量增加，“In the next century,  “在下个世纪比较高的气温和湿度将会变得很正常，但产量下降，唯一的不同就是没有“气候通常较冷”这个条件，也是唯一的突破口，通常较冷的气候会让害虫无法生存，即便温度升高湿度加大也不会立即产生大量的害虫，只有当气候一直都暖和且湿度加大才能大量产生害虫。

xw909

题目有好几个时间概念，“In recent years .”指的是最近几年气候通常较冷。“But during periods ”指的是最近在一些时期气候和湿度比较高的时候粮食产量增加，“In the next century,  “在下个世纪比较高的气温和湿度将会变得很正常，但产量下降，唯一的不同就是没有“气候通常较冷”这个条件，也是唯一的突破口，通常较冷的气候会让害虫无法生存，即便温度升高湿度加大也不会立即产生大量的害虫，只有当气候一直都暖和且湿度加大才能大量产生害虫。

-- by 会员 kenhu (2010/7/5 13:06:04)

恩，我也这么想的，但是虫子生长这种特性是成指数的，这种概念不是题里面给的啊，这个可以用么？题目里面没说，你怎么知道虫子开始增长的很缓慢，温度增加到一定程度才开始快速增长并且对庄家造成危害呢
你说的是事实，但是不是gmat世界里面的事实啊

kenhu

The climate in northern Asia has generally been too cool and dry in recent years for populations of many crop insect pests to become established.
C选项给出了，但是题目没有告诉你温度升高虫子增多，所以In recent years 温度低是害虫少的原因。你只要利用题目给的信息很容易就能选出C来。

xw909

The climate in northern Asia has generally been too cool and dry in recent years for populations of many crop insect pests to become established.
C选项给出了，但是题目没有告诉你温度升高虫子增多，所以In recent years 温度低是害虫少的原因。你只要利用题目给的信息很容易就能选出C来。

-- by 会员 kenhu (2010/7/5 21:25:26)

你还没明白的我意思啊，我想不明白为什么气温短暂升高了，庄稼却增产了，虫子哪去了呢

kenhu

首先气温升高导致庄稼增产这是题目给出的信息，况且题目也没给出害虫的信息，害虫是在选项C中出现是为了解释题干。其实题目的信息很简单，critical thinking只要求你从题干找信息。

xw909

首先气温升高导致庄稼增产这是题目给出的信息，况且题目也没给出害虫的信息，害虫是在选项C中出现是为了解释题干。其实题目的信息很简单，critical thinking只要求你从题干找信息。

-- by 会员 kenhu (2010/7/5 23:36:30)

基本明白了，十分感谢，巨讨厌这考试，没办法啊，呵呵