This is a passive voice sentence
the active voice is "A dentist invented the electric chair"
So the subject is dentist
Hope I helped !
Having a doctors note to stay home for 4 days cancels out in school work, online is at home, which you still have, unless your doctor says no work at all.
“Mary was described as a sour, hateful “little pig” (Burnett 4).” is most likely the correct answer.