GWD 5 -26

Q26:

If r, s, and t are positive integers, is r + s + t even?

(1)     r + s is even.

(2)     s +
                        t is even.

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E

我选的是C, 因为只有EVEN + EVEN = EVEN, ODD + ODD = EVEN,所以知道R+S AND S+T是因为可以确定的呀....能不能帮忙解释一下...

没有人可以帮忙解释解释吗??? 或者答案是错的???

我用的是GWD-31套, 题号不一样,找不到解释的贴子.....

当r、s、t全部是奇数的时候，则三数之和是奇数，当r、s、t三数全是偶数的时候，则三数之和是偶数，所以无法判断。不知道我的理解对不对