几个月过后我就是一名高中生了。 英语翻译

Answer 1

“就要” 也就是 “在不久后客观存在的未来”，适于用 be going to 或 be becoming。

译文

～I'm going to be a high school student of in a few months.
～I'm becoming a senior student of a high school in a few months.

Answer 2

I will be a high school student in a few months

Answer 3

A few months after I was a high school student.