One should take note that participles ending in -inta and -ita indicate action that was completed before or at the time indicated by esti — that is, la fenestro estis fermita kiam Fafa eniris la ĉambron (“the window was closed when Fafa entered the room”) can mean that the window was closed either at some time prior to Fafa’s entry or simultaneously with it. To indicate that the window was closed before Fafa entered, use jam (“already”) or, better yet (since jam can mean both “before then” and “starting from then”), antaŭe (“previously”): la fenestro estis antaŭe fermita kiam Fafa eniris la ĉambron “the window was already closed when Fafa entered the room”. To indicate that the door was closed at the same time Fafa entered, use tiam (“then”): la fenestro estis tiam fermita kiam Fafa eniris la ĉambron “the window was closed (right) when Fafa entered the room”.