After __ seemed an endless wait,it was her turn to enter the personnel manager’s office.

介词after+名词；
介词after+动名词；
介词after+相当于名词的短语或从句；
连词after+时间状语从句.
如：
He went to school after eight. (介词+名词）
After waiting for a long time, he went away. (介词+动名词）（注：动名词相当于一个名词.）
He began his school after a long wait.（介词+名词性短语）（注：名词性短语相当于一个名词）
After _what__ seemed an endless wait, it was her turn to enter the personnel manager’s office.(介词+名词性从句）（注：what引导的从句都是名词性从句,这种从句相当于于一个名词.）
He went to school after the clock stuck eight. (连词+时间状语从句）
此例不好改成连词after引导的时间状语从句,硬要改而且意思不能有变的话,可以加一个插入语：
After she waited for a long time, one that seemed endless, it was her turn to enter the personnel manager’s office.
祝你学习进步,更上一层楼! (*^__^*)
不明白的再问哟!请记得采纳,多谢!我已经在例句中说了，这个after是介词，后面接了一个名词性从句。网上说如果是连词，从句的时态常用完成体。这种说法不太靠谱，after引导的时间状语从句也常用一般过去时，甚至也可用一般现在时、一般将来时。