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 statement above is 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 wihthin two business days of being sent is correctly addressed.
D. A larage 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 senet.
A, B,C, Edoes not seem to be true to me, so I pick up D, and D is the right answer, but why?
D其实来源于原文第一句话和最后句话
第一句话：ADDRESS正确------〉两天内到达（逆否命题：两天内没到达----〉ADDRESS不正确）
最后一句话：多数MAIL超过三天（即两天内没到达）
第一句话和最后句话结合就是ADDRESS不正确。
Aside from (D), (A) is also possible by the similar vain outlined above.
No, it is not like that. This is a different type, not a reasoning on formal logic formula, but a reasoning on SET (集合), and the inference can only be surely drawn by diagraming the relations of set and its subsets.
Let's see:
We know that nearly all mail that is correctly addressed arrives within two business days. The only mail that doesn't arrive within two business days is (1) damaged mail and (2) incorrectly addressed mail. Because we know that nearly all correctly addressed mail is not damaged, the fact that most mail arrives three business days or more after being sent can be read to indicate that there is a bunch of incorrectly addressed mail, which is the answer (D)
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