我妹妹成为大学生已经三年了。的翻译：My sister has become a college student for three years. 什么意思？中文翻译英文，英文翻译中文，怎么说？

青云英语翻译

My sister has three years to become college students.

My sister has become a college student for three years.

My younger sister became the university student already three years.

My sister became a college student has 3 years.

My sister has become a college student for three years.