I'm a doctor in Beijing. 我在北京是医生 →我在北京当医生。 He is also a teacher in China. 他在中国也老师→他也是一位在中国工作的老师。 My friend is French and lives in Sydney. 我的朋友是法国人。他住在悉尼。→我的朋友是个法国人，住在悉尼。 The order is different in different sentences. For example， when someone tells you that he is a teacher, you can say “我也是个老师，在中国工作” or “我也是个老师。我在中国工作”。 Both sentences are proper. But when you are making a statement, it it better to say the information in one sentence. 比如：我叫Li，是个学生，来自中国。 Especially when there are more than two points. But in your case, since there is just two short sentences, it is okay to say these seperately.

我是北京的医生。 他是中国的老师。

maybe you could translate it :我在北京当医生。and the next sentence:他在中国,也是一位老师.but i think we seldom say like that.i think we say:我的朋友是法国人。他住在悉尼,more usual. your question also makes me confuse .....