Cracking the LSAT 上的一道题目，为什么感觉有问题？还是我是逻辑白痴－－

dukesena · 发表于 2008-2-2 11:15:00

2006年版的，上来的ARGUEMENT里ASSMUPTION QUESTION例题2；

Beacuse my gas mileage has been steady during the same time period, the alignment of my car's

wheels must be normal.

问ASSMUPTION,
其中一个选项是：

A drop in gas mileage occurs only if a car's wheels are out of alignment.

另外一个是：

Misaligned wheels can sometimes cause a car's mileage to drop.

我上来第一感觉就选了第一个，但是答案说是第二个，解释的不是很明白，望坛子里的各位指点，刚接触LSAT见笑...

poppyxams · 发表于 2008-2-3 13:21:00

我觉得哈，第一个不太对的地方是它把范围限定得不必要的小，就是只有wheels are out of alignment时gas mileage 才出问题，事实上其他故障也可能会导致这个问题，那么如果出问题就无法得出是不是wheels出故障了，但是如果什么问题都没有，那肯定wheels也没问题；第二个恰到好处不浪费，说wheels 故障会导致问题，（不排除其他故障的情况）但是只要什么问题都没有，就说明wheels没问题。

所以可能第二个会稍好一点。

dphxmg · 发表于 2008-2-3 18:11:00

The stem: drop¬ --> normal; its equivalent statement is: normal¬ --> drop

A drop in gas mileage occurs only if a car's wheels are out of alignment: drop --> normal¬. Well, you can see that it confuses the necessary condition with the sufficient condition.

Misaligned wheels can sometimes cause a car's mileage to drop. If we negative this statement, then we have the statement: (normal¬ -- drop)¬. You can see this statement is in conflict with the statement implied in the stem. So it is the key.

cbb2 · 发表于 2008-2-23 08:23:00

Beacuse my gas mileage has been steady during the same time period, ---------A

CONCLUSION: the alignment of my car's wheels must be normal.----B

GAP: A---B

NOT B-----NOT A is also correct

问ASSMUPTION,
其中一个选项是：

A drop in gas mileage occurs only if a car's wheels are out of alignment.

This one is not A---NOT B. MISTAKEN NEGATION

另外一个是：

Misaligned wheels can sometimes cause a car's mileage to drop.

This one is NOT B----NOT A, CONTRAPOSITIVE.

Cracking the LSAT 上的一道题目，为什么感觉有问题？还是我是逻辑白痴－－