A．正确 B．错误……

单项选择题下列 程序段实现图中IN4的1次A D转换，转换结果保存在AL寄存器中。 A、 MOV AL,04H MOV DX,0348H OUT DX,AL MOV DX,0349H AA: IN AL,DX TEST AL,08H JZ AA MOV DX,0348H IN AL,DX HLT B、MOV DX,0348H OUT DX,AL MOV DX,0349H AA: IN AL,DX TEST AL,08H JZ AA MOV DX,0348H IN AL,DX HLT C、 MOV AL,04H MOV DX,0348H OUT DX,AL MOV DX,0349H AA: IN AL,DX TEST AL,10H JZ AA MOV DX,0348H IN AL,DX HLT D、 MOV AL,04H MOV DX,0348H OUT DX,AL MOV DX,0349H AA: IN AL,DX TEST AL,08H JNZ AA MOV DX,0348H IN AL,DX HLT

单项选择题题7中,总体的第二主成分及其解释的方差比例为( )