Spanish and English share much vocabulary--necesario, requirir, demandar present no obstacle to the English speaker, and English words of Latin extraction have their Spanish parallels.
A wrinkle in the Latin fabric of our languages: I noticed in the past week or so a that a Mexican businessman, writing in English, described certain items as "exigible"; and a film-music composer described Pedro Almodóvar as a "very exigent director." An exigible item is one an English speaker would describe as, according to the Random House Dictionary of the English Language, 2d., "liable to be exacted; requirable"*--but my point is that an English speaker probably wouldn't. "Exigible" is just not used by modern English speakers. The same goes for describing a person as "exigent"--we'd just say "demanding," but a Spanish-speaker would still describe his boss as exigente. (I think English speakers would still say a situation is exigent.)
I still remember "El Exigente," by the way.
*Sic; not "requireable?"