题干
—I'm late for your party an accident. I'm sorry.
—It doesn't matter. Enjoy yourself here.
A：ahead of
B：Instead of
C：because of
答案(点此获取答案解析）
C
目标函数z＝y－ax(a∈R)，若z取最大值时的唯一最优解是(1,3)，则实数a的取值范围是