179. When impersonal verbs, or other verbs used impersonally, are in
compound tenses, the participial element is given the ending "-e", like
other modifiers of impersonally used verbs (141):
Estis pluvante antaux unu minuto, it was raining a minute ago.
Estis multe negxinte, it had snowed a great deal.
Estis vidate ke cxiu ploras, it was seen that every one wept.