A:Ba(OH)2 =Ba2++ (OH)-
B:FeCl3=Fe2++3Cl-
C:H2SO4 =H2++SO42-
D:Al2(SO4)3=2Al3++3SO42-
已知变量x,y满足约束条件y+x-1≤0y-3x-1≤0y-x+1≥0则z=2x+y的最大值为 ( )
下列各组的两个图形属于全等图形的是 ( )
从方框中选出下列各句的最佳应答语。
A.I'm drawing a picture.
B.Yes,it can.
C.No,she isn't.
D.They're Liuwei's.
E.They're having dinner.