They are slightly different. I'm = I am I've been = I Have been By saying "I am left holding the baby" you mean that you are currently, at the present, holding the baby. By saying "I have been holding the baby" you mean that you aren't not currently, at the present, holding the baby, but you have held it (the baby) before in the past. Regards, Alex

To suddenly have to deal with a difficult problem or responsibility because someone else has decided they do not want to deal with it. = to be left holding the baby. To be holding the bag =To be left with empty hands. To be forced to assume total responsibility when it ought to have been shared.