CXDpage47 No.28

CXD的书PAGE 47

No.28     Springtown’s fire department wants the town council to buy it another ladder truck. These trucks are useful in fighting fires in high-rise buildings. The town council argues, however, that springtown has only two high-rise buildings, and it already owns enough ladder trucks to fight any fires there. So, they say, Springtown does not need another ladder truck.’

The town council’s argument assumes that

A)     Springtown cannot afford to buy another ladder truck

B)      Springtown’s high-rise buildings all meet or exceed current fire safety standards

C)     The number of high-rise buildings in Springtown is likely to grow

D)     At least one of Springtown’s ladder trucks is not due to be permantly removed from service in the immediate future

E)      It is possible to fight fires successfully in high-rise buildings without using ladder trucks.

这个题目，自由是做对的，自由运用的是排除方法，A，B是同原文无关，所以直接排除。而C是对原文的削弱而不是加强，假设其实是一种很特殊的加强，所以C也排除。而E是同原文中“These trucks are useful in fighting fires in high-rise buildings” 对原文客观事实的篡改，所以干脆排除。因此正确答案是D，但是自由在重新仔细看这个答案是的时候，有个逻辑上的疑问，请大家帮忙。疑问是，如果如D所说，至少有一个ladder truck，就是说，可以只是存在一个ladder truck那么原文中是城市里两个高层建筑，我们可以假设，如果两个高层建筑同时有火灾，那么D不是不成立吗,因为一个ladder truck怎么可能同时救济2个高层建筑呢？自由比较喜欢钻牛角尖，而且老外好象逻辑思维要滴水不漏，所以请教各位逻辑高手，自由这个牛角尖，应该如何根据ETS出庭的思路来很好的化解呢？感谢大家的宝贵帮助。

assumption是结论的必要条件，也就是“题干的premise＋题支的assumption”不一定能推出结论，但是从结论一定能推出assumption。

具体这道题：“至少一个truck好使”的确推不出“安全完全有保障”，像你假设的情况一样；但是“安全完全有保障”一定推得出“至少一个truck好使”。所以“至少一个truck好使”就可以做assumption。