218. The suffix "-ad-" is used to form words indicating that the action
expressed in the root is continuous, habitual or repeated.
a. Verbs formed with the suffix "-ad-" are called "frequentative
verbs", and may often be translated by the root meaning, preceded by
"keep (on)", "used to", etc.:
frapadi, to keep knocking, to knock repeatedly.
rigardadi, to keep on looking, to gaze.
vizitadi, to keep visiting, visit repeatedly, frequent, haunt.
Antaux du jaroj sxi tre dolcxe kantadis,
two years ago she used to sing very sweetly.
b. Nouns formed with the suffix "-ad-" are often equivalent to English
verbal nouns ending in "-ing", and (with the generic article, 201) may
replace the infinitive as subject (130) and sometimes as object (29):
kriado, crying, shouting (from krio, cry, shout).
movado, motion, movement in general (from movo, a movement).
pafado, shooting, fusillade (from pafo, a shot).
parolado, a speech, address (from parolo, a word spoken).
pensado, thought, contemplation (from penso, a thought).
La promenado donas plezuron, the taking of walks gives pleasure.
Mi preferas la legadon de tiaj libroj,
I prefer the reading of (to read) such books.