请教一题

juneyingmao

63. Some good cooks are gourmet cooks who pride themselves on always using extravagantly rich ingredients in elaborate recipes. Some good cooks can be characterized as fast-food cooks. They may use rich ingredients as long as the recipes are easy to follow and take little time. Other good cooks are health food enthusiasts, who are concerned primarily with the nutritional value of food. But even though not all good cooks are big eaters, they all enjoy preparing and serving food. 

 If the information in the passage is true, which one of the following CANNOT be true? 

 A.        Most good cooks do not use extravagantly rich ingredients. 

B.        Everyone who enjoys preparing and serving food is a good cook. 

C.        More good cooks who use extravagantly rich ingredients are big eaters than are good cooks who do not use such ingredients. 

D.       There are fewer good cooks who enjoy serving and preparing food than there are good cooks who are big eaters. 

E.    Gourmet cooks, fast-food cooks, and cooks who are health food enthusiasts are all big eaters.
        

答案是D，可以理解，但是其他为什么不对呢，我看B啊，E啊，都貌似cannot be true的啊

xfi883

BE选项从逻辑上讲太绝对，但从题目看，还是有可能推出的。作逻辑题时，应抛弃自己的常识，注意题目本身。

edmundshi

按描述画个文氏图就出来了～

全集是：good-cooks

GC：gourmet cooks

FC：fast-food cooks

RI：rich ingredients cooks （为GC与FC的交集）

HFE：health food enthusiasts

之后又一个big-eaters是GC.FC.HFE的交集，图上没标出，可以自己想个小圆覆盖在大圆上，然后推得C can be true

[attachimg]71691[/attachimg]

B中：good cooks enjoy preparing and serving food 只能说明 good cooks 是 people who enjoy preparing and serving food的子集，全集不能推出真子集

[此贴子已经被作者于2009-7-7 16:53:40编辑过]

juneyingmao

恩，大概能体会到一点了，是不是这么理解，B：每个enjoy的人都是好厨师，B not true的话，就是说enjoy的人都不是好厨师，但是其中有些是好厨师，有些不是，所以不能选，E也雷同，可以这么理解吗

edmundshi

嗯～

还试图更能说明问题点～

以B为例：

[attachimg]71702[/attachimg]