Hm! Duo accepted "This man doesn't work here any more" but said I "have an extra space" in 'any more'.
At https://www.duolingo.com/comment/12730282 we earlier agreed that 'any more' (as opposed to the US English 'anymore') is correct in the UK and should be included as an incubator option...
I still do not see why it wants gentleman instead of man, when it is merely another word for 'man'. If you try to twist the learner's language to fit the new language it might suit your lesson, but untwists immediately in the learner's mind and twists the new language. And since the learner's language is much more advanced, it twists the new language in ways unimagined by the teacher. Teach the new language in the new language.