Questions & Answers about La fenestro malrapide fermiĝas.
Fermiĝas comes from fermi (to close) + the intransitive/middle suffix -iĝ- + present tense -as:
- fermi = to close (something)
- fermiĝi = to get closed / to become closed / to close (by itself)
- fermiĝas = is getting closed / is closing
So:
La viro fermas la fenestron. = The man closes the window.
(fermas: someone is doing the action to an object)La fenestro fermiĝas. = The window closes / The window is closing.
(fermiĝas: the window undergoes the change of state; no explicit “closer” mentioned)
-iĝ- turns a transitive idea (fermi = to close something) into an intransitive change-of-state (fermiĝi = to become closed).