They have accents because nearly every country has a different one and that can't be helped!
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Although I have yet to find the exact cause of the change in spelling, I can provide the following print history of the word's evolution. While the word "mamma" was created during the Elizabethan renaissance, the word "mum" first appeared in print in 1823. In 1839, this spawned "mummy". It wasn't until 1884 that the O was used in "momma". This was, of course, shortened to "mom" in 1894. My unproven theory is that somebody thought "mother" was spelled with an O so "mamma" should be spelled that way as well.
No. Now, if you spell it out as "televisión", you do use an accent mark.
habitacion (accent on the 'o') cuarto
celebracion accent over the "o"
its just the same but it has an accent over the "O"
It's the same, Ramon, but with an accent on the 'o'
pasó progreso (accent on final 'o')
'pavon' OR 'pavo real' (accent on the 'o' in 'pavon')
xilofono, xilorgano (both with accent on middle 'o') = xylophone
It would be written as: eleccion (accent over the 'o') presidencial.
'(To) pumice' (verb) = 'apomazar' in Spanish 'pumice stone' = 'piedra pomez' (with an accent on the 'o')
Como estas (informal) Como esta usted (formal) (In each case, with an accent over the first 'o', and the 'a')
There are no distinct spellings other than the formal English, "suggestion".