excel if公式写法

=IF(ISBLANK(O52),IF(ISBLANK(L52),"填写上个时间",IF(TODAY()-(L52+M52)>0,"还有"&TODAY()-(L52+M52)&"天到期",IF(TODAY()-(L52+M52)<0,"已过期",IF(TODAY()-(L52+M52)=0,"今日过期")))),"完成")

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