这句英文的逻辑关系是什么
问题描述：
这句英文的逻辑关系是什么
A visa can be extended such that the total period of residence in the Schengen area is a maximum of 90 days in the course of the last 180 days.
答
申根区签证可以在现有居留权的最后180天内申请延期,最多可将居留权延长90天.