They were invited to an important ball ___the first time in their lives

题目

They were invited to an important ball ___the first time in their lives
正确答案填for.为什么不用in?

答案

for the first time表示作为第一次,首次；第一次.表示有生以来或一段时间内第一次做某事.For the first time,I am looking in your eyes.
for的用法有很多 比如你说的for+时间段,这通常用于完成时态.
for也可以表示原因,for some reason,也可以表目的,for sth or sb.
for the first time 首次；第一次.表示有生以来或一段时间内第一次做某事