变量x,y满足约束条件{x+y≥0x-2y+2≥0mx-y≤0,若z=2x-y的最大值为2,则实数m等于( )
例
uncle
Play tennis
1
aunt
Playing football
2
sister
Playing basketball
3
teacher
Playing ping-pong
4
mother
Playing volleyball
例:My uncle is playing tennis.
下列句子中划线词语使用不恰当的一项是( )