Final answer:
Stuart did three things that an ordinary boy could not possibly do: painting a portrait of the President, living in London and Ireland, and aspiring to create European Grand Manner portraits.
Step-by-step explanation:
In Stuart's case, there are three things that an ordinary boy could not possibly do:
Stuart had the opportunity to paint a portrait of the President.
This is not something an ordinary boy would have the chance to do, as it requires advanced artistic skills and connections.
Stuart lived in London for twelve years and then relocated to Ireland.
This extensive travel and experience in different countries is not something an ordinary boy would typically have the opportunity to do.
Stuart aspired to paint American versions of European Grand Manner portraits, similar to Hyacinthe Rigaud's painting of Louis XIV. This level of artistic ambition and skill is not common among ordinary boys.