再请教思路

assurance

If C and D are integers, is C even?

(1)c(d+1)even

(2)(c+2)(d+4)even

answer: C

assurance

I got it,thanks !!!

poorleafs

（1）c(d+1)even，说明c even 或者d+1 even 或者 both even

(2))(c+2)(d+4)even说明c+2 even或者d +4even或者 both even

综合，因为d+1和d+4不可能同时 even,因此只有c even.