GG13-Set 7/

Q36:

If a and b are positive integers such that a-b and a/b are both even integers, which of the following must be an odd integer?

A. a/2

B.b/2

C. (a+b)/2

D. (a+2)/2

E. (b+2)/2

根据题目给的前提，可以推得a, b都是偶数。那么D和E都势必是奇数了，不知道这样的推理有没有错？答案是D,想不通为何E不对...

谢谢！