________ English is very good. ( )
A:She
B:Her
C:Hers
设实数x,y满足条件4x-y-10≤0x-2y+8≥0x≥0,y≥0,若目标函数z=ax+bya>0,b>0的最大值为12,则2a+3b的最小值为( )
①ZnC2
②Al4C3
③Mg2C3
④Li2C2.