Q36: If x, y, and z are positive integers, is xz even? (1) xy is even. (2) yz 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. Answer:E ------------------------------------------------------------------------------------------------------------ 看了GWD讨论链接似乎没有讨论过本题。我选的是C。不知道是不是理解错了。我认为，一个奇数的因子必然都是奇数，所以1)推出x，z是奇数；2）推出y，z是奇数。所以两个奇数x,z相乘也是奇数。不知道错在哪里？请指点。谢谢。 | 
