it was several months ( )i was able to have a day off to visit my parents.为什么用before?

题目

it was several months ( )i was able to have a day off to visit my parents.为什么用before?
是才的意思?
但我觉得几个月已经蛮长了啊
为什么不是that 定语从句?
如果用that 定语从句应该怎么改？

答案

it was several months (before)i was able to have a day off to visit my parents.意思是"几个月后我才能休息一天去看望父母.",直译是"在我能休息一天去看望父母之前要有几个月".如果用that引导定语从句,意思就不对了,语法也不对.