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

it is 3 years since he has been a doctor 怎么翻? It is 3 years since he joined the army.为什么用is不用has been It has been 3 years since he came here. it is 3 years since Tom has been abroad It is a week since he has been to BeiJing. 看到一句It is 3 years since he joined the army.和一句It has been th "It has been ten years since he was a teacher."这句话有什么错误?可以怎么 分析一下它的含义?It is has been four years since he lived here． 翻译 It's five years since he smoked It has been 2 years since It has been several years since he lived here.怎么翻译? it is ten years since he became a doctor同义句 tim has been a doctor for many years ,so he is an ____doctor