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标题: [求助]涛涛GWD6 [打印本页]

作者: Sarah006 时间: 2006-8-5 10:26
标题: [求助]涛涛GWD6
26

K is a set of integers such that if the integer r is in K, then r + 1 is also in K. Is 100 in K?

(1) 50 is in K.

(2) 150 is in K.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案是A,不知道是怎么算出来的？？谢谢帮忙

作者: lovetiky 时间: 2006-8-5 17:05

if 50 is in K, then 50+1 is in K, then 51+1 is in K, then ... then 99+1 is in K

but if 150 is in K, we can not assure that 100 is in K, maybe the minimum in K is greater than 100

作者: Sarah006 时间: 2006-8-5 19:14

谢谢，说得很明白

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