I often Linda the old woman with housework last year.
A:see; helps
B:saw; helps
C:saw; helped
D:saw; help
若实数x,y满足不等式组{x-2≤0y-1≤0x+2y-2≥0,则x-y的最小值为( )
已知a→,b→是非零向量且满足(3a→-b→)⊥a→,(4a→-b→)⊥b→则a→,b→的夹角是( )
如果+12=0,那么内应填的数是( )