[讨论]再次问一下GWD-30-18。答案似乎有争议

liaochuanjie

Q18:

If k is a positive integer, is k the square of an integer?

(1)   k is divisible by 4.

(2) k is divisible by exactly 4 different prime numbers.

                  

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.

                                                                                                  Answer: E

在此之前已经浏览了相关帖子：http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=173753&replyID=1638459&skin=1

http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=174820&replyID=&skin=1

http://forum.chasedream.com/dispbbs.asp?BoardID=22&ID=185266&replyID=&skin=1

可是小弟还是没能得出最后结论。这道题到底是B还是E？

我选B的理解是：

k这个数只能被4个质数整除。这里有点文字游戏：不知道是只能有4个数而且都是质数，还是说是4个质数，但是可以有几个相同的质数：情况1：2，3，5，7； 情况2：（2，2，3，3，5，5，7，7，）＝(2×3×5×7)²。我是按情况1进行理解的，所以选的B。

不知道大家怎么看呢？谢谢

laoitao

我感觉是E，lz提出的是不是一种特殊情况呢？

liubin1987

LZ给的条件2其实也是只有四个不同的质数啊...

mingyuexing

 正因为有两种情况，所以最后才不能确定是否K是某个整数的平方啊