180. To give a reciprocal sense, when there are two or more subjects and
the action goes from one to the other (expressed in English by "each
other," "one another," "mutually," "reciprocally"), the phrases "unu la
alian", "unu al la alia", etc., or the adverb "reciproke", is used:
Estas nia devo helpi unu la alian,
it is our duty to help one another.
Ili parolas unu al la alia,
they are talking to each other.
La viroj reciproke uzis siajn pafilojn,
the men used each other's guns.
Ili falis unu sur la alian,
they fell upon each other.