=if(or(a1="北京",a1="上海",a1="南京"),"中国","国外")
=IF(OR(A1="北京",A1="上海",A1="南京"),"中国","国外")
=IF(OR(A1="中国",A1="国外")
用一条竖杠"|"或两条竖杠''||''
一般或着用||就行的啊