LSAT-24-4-19

mythicalman

Nearly all mail that is correctly addressed arrives at its destination within two business days of being sent. In fact, correctly addressed mail takes longer than this only when it is damaged in transit. Overall, however, most mail arrives three business days or more after being sent.

If the statements above are true, which one of the following must be true?

(A) A large proportion of the mail that is correctly addressed is damaged in transit.

(B) No incorrectly addressed mail arrives within two business days of being sent.

(C) Most mail that arrives within two business days of being sent is correctly addressed.

(D) A large proportion of mail is incorrectly addressed.

(E) More mail arrives within two business days of being sent than arrives between two and three business days after being sent.

D

请解释一下为什么选D，A和C为什么不对？

番茄炒蛋

我觉得选C
因为A和D都是一样的，没有什么区别啊，确定不了
只有C才是符合文章原意的

高人再看看吧

mariezhu

Mail
  Nearly all correctly addressed: 2 days
    only when damaged： more time
  Most mails take more than 3 days.

then many mails are not correctly addressed.

mythicalman

请问，如何排除A和C?

dorbear

[face=Verdana]Nearly all mail that is correctly addressed arrives at its destination within two business days of being sent. In fact, correctly addressed mail takes longer than this only when it is damaged in transit. Overall, however, most mail arrives three business days or more after being sent.

If the statements above are true, which one of the following must be true?
(A) A large proportion of the mail that is correctly addressed is damaged in transit.
(B) No incorrectly addressed mail arrives within two business days of being sent.
(C) Most mail that arrives within two business days of being sent is correctly addressed.
(D) A large proportion of mail is incorrectly addressed.
(E) More mail arrives within two business days of being sent than arrives between two and three business days after being sent.
=========================================
This is a pure Deduction, have to stick to the logic diagram instead of taking for granted to form the conclusion, now let's get down to it:

The passage contains two conditional statements and one conclusion:
1. Correctly addressed => within two business days (A -> B)
2. Correctly addressed X Not (within two business days) => damaged in transit.((A .NOT. B) => C)
Conclusion: most mail arrives three business days or more after being sent. (.NOT. B)

With the rule of contraproductive, we know .NOT. B => .NOT. A, this is the answer (D). Other than the above, we just can't deduce anything else from .NOT. B, meaning we don't know (A) which is AC, (B) which is B .NOT. A, (C) which is AB, or (E) B.

Hope it clarifies.[/face]

mythicalman

版主写得太好了。
我问了一个英语牛人：
他说 in fact 是让步，削弱语气，说明从属前者。所以可以略去不看。这样，就可以直接推出来了。大家参考一下。
还是版主写得清楚。

番茄炒蛋

这个逻辑关系真是巧妙，呵呵，开始真就没想出来，高人
楼上小MY说的也不是没有道理，不过考试的时候还是不敢用