指出下列各条指令中源操作数的寻址方式,并指出下列各条指令执行之后,AX寄存器的内容。设有关寄存器和存储单元的内容为:(DS)=2000H,(BX)=0100H,(SI)=0002H,(20100H)=12H,(20101H)=34H,(20102H)=56H,(20103H)=78H,(21200H)=2AH,(21201H)=4CH,(21202H)=087H,(21203H)=65H: (1)MOV AX,1200H (2)MOV AX,BX (3)MOV AX,[1200H] (4)MOV AX,[BX] (5)MOV AX,1100H[BX] (6)MOV AX,[BX],[SI] (7)MOV AX,1100H[BX],[SI]