​(06/15/21)

-난 4년 후에 나의 학위를 획득했다. I got my scholar after four years.

*I obtained my degree in four years. 

~> Your sentence has a correct grammatical structure, but this has the correct usage/expression. ​

-나의 영어 실력은 몇 년 동안 향상되었다. My English skill has raised within few years.

​*My English skills improved over the years.

~> Your sentence has a correct grammatical structure, but this has the correct usage/expression. ​