ChaseDream

标题: TTGWD6-26 [打印本页]

作者: 苹果虫 时间: 2006-10-19 20:29
标题: TTGWD6-26

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，这种题该怎么理解？为什么只能往上加？我怎么觉得往上加往下加都可以啊？请战友们指教

作者: kenworth 时间: 2006-10-19 20:35
r有可能从>100的数开始啊

作者: Sacramento_CA 时间: 2007-6-20 12:26
这题我就是看不明白，觉得应该选D啊。哪位能给解释一下吗？

[此贴子已经被作者于2007-6-22 23:33:08编辑过]

作者: sammy生米 时间: 2007-6-20 19:53

是的，这题只能往上加，不能想当然往下减的

如该数列从150开始，按题意151在该数列内，但100就不在该数列了

作者: renbenzhuyi 时间: 2007-6-23 06:17

(2)可以保证所有>150的都在S内，但不能保证<150的也在S内。

(1）保证所有>50的都在S内

欢迎光临 ChaseDream (https://forum.chasedream.com/)