没过几天的英文

before long~not long after~

But you will go in the coming days

soon after例:.He arrived soon after three. 三点才过他便到了。

Every few days

but you will leave here in some days later

例如每隔两天：every two days

long before与before long的区别如下：long before意为很久以前 而before long意为不久以后（即你所问的“没过多久”的意思）。例：Long before，this village is the trade centre of the nearby areas. 很久以前，这座村庄是当地的商贸中心。The sky turned dark suddenly, before long, fat drops of rain followed.天突然暗了下来，不久就下起了瓢泼大雨。