XOR AX,AX MOV AL,90H CWD 执行上述指令后,结果为（)A （DX=0000, （AX=FF90HB （DX=FFFFH,（AX=0

XOR AX,AX MOV AL,90H CWD 执行上述指令后,结果为()

A (DX=0000, (AX=FF90H

B (DX=FFFFH,(AX=0090H

C (DX=FFFFH,(AX=FF90H

D(DX=0000, (AX=0090H