after what seemed an endless wait 是时间状语从句,从句套从句,what 引导的从句作介词after的宾语,wait是名词 等待
it was……to enter……是主句,it作形式主语,真正的主语是不定式 to enter the personnel manager's office,turn 是名词,硬要翻译大概可以翻译成“轮到某人的机会”吧
翻译:在经历了一番看起来是无尽的等待之后,轮到他进入人事部经理的办公室
(After what seemed an endless wait), it was his turn (to enter the personnel manager's office)
状语 主 谓 宾 宾补