it is 3 years since he has been a doctor 怎么翻?

问题描述:

it is 3 years since he has been a doctor 怎么翻?
还有it is 3 years since he was a doctor 怎么翻译1?

前一句:他已经当医生三年了.
后一句:自从他不当医生已经三年过去了.