我从事机械设计已有四年了的翻译：Four years since I engaged in mechanical design 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

I have four years in the mechanical design

Four years since I engaged in mechanical design

I am engaged in the machine design to have four years

As I have been engaged in the mechanical design has 4 years

Four years since I engaged in mechanical design