谁能帮我解释下下面的公式怎么解释,尤其是后面IF(LEFT(D3,3)="LZW","柳机",""))这个
=IF(OR(MID(C3,8,1)="A",MID(C3,8,1)="B",MID(C3,8,1)="K",MID(C3,8,1)="M",MID(C3,8,1)="Q"),"B系列",IF(LEFT(D3,3)="LZW","柳机",""))