设(DS)=2000H,(ES)=2100H,(SS)=1500H,(SI)=00A0H,(BX)=0100H,(BP)=0010H,数据变量VAL的偏移地址为0050H,请指出下列指令的源操作数字段是什么寻址方式?它的物理地址是多少? (1) MOV AX,21H (2) MOV AX,BX (3) MOV AX,[1000H] (4) MOV AX,VAL (5) MOV AX,[BX] (6) MOV AX,ES:[BX] (7) MOV AX,[BP] (8) MOV AX,[SI] (9) MOV AX,[BX+10] (10) MOV AX,VAL[BX] (11) MOV AX,[BX][SI] (12) MOV AX,VAL[BX][SI]