GWD7-36

[liwuu]

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

答案是D...請問除了try and error外,是不是有其他正規方法...抓不到此題技巧
謝謝!!

[huacy]

http://www.formosamba.com/phpBB3/viewtopic.php?t=587

[liwuu]

感謝h大提供...謝囉!!