some confusion

discard2

Is x+z=y? 1) |x| = y+z 2) x<0 -->C i think the key is E,isn't it? DS: is M divisible by 12 ? 1)M/3 rem 1 2)M/4 rem 3 D i think the key should be C,right?

discard2

why nobody answer me?I will take the test 3 days later,thank you.

tongxun

1、x+z=y, x=y-z.
condition 1: |x| = y+z  , x=-y-z, or x=y+z.  因此，x 从等式上看不等于y-z。但X、Z、Y都等于0，则可使x=y-z成立。
条件2：不充分。
条件1+2：得x=-y-z ，且X不等于0，所以充分。
答案应该是C
2、D。
若整除12，则必包含因子3、4。

cook

1. I agree on E. Don't forget the condition when Y=0, then x=-z.
2. D  , Discard2, why not give us a example on you stand?

tongxun

1、我简直疯了！as cook said the condition when Y=0, then x=-z。if z=1，z=1。
  是E。