przymoitniki:
open - otwarty, closed - zamknięty
czasowniki:
opened - otwierany, closed - zamykany
This shop is opened at 8 a.m. and closed at 5 p.m.
It is open from 8 to 5.
It is closed between 5 p.m. and 8 a.m.
jak widzisz, closed ma dwa znaczenia
Dodam jeszcze, że zamiast 'jest otwierany' i 'jest zamykany' naturalniej powiedzieć po angielsku: the shop opens at 8 and closes at 5