• 1. (2019九上·阳新期末) 若把x﹣y看成一项，合并2(x﹣y)²+3(x﹣y)+5(y﹣x)²+3(y﹣x)得（   ）

  A . 7(x﹣y)² B . ﹣3(x﹣y)² C . ﹣3(x+y)²+6(x﹣y) D . (y﹣x)²