to use / to employ / to make use of, to apply / to spend

the past / ancient times

old

(not of a person) old, aged, antiquated

tool (mechanical device intended to make a task easier) / a means, something used to perform an operation

age, era, period (of time) / the times, spirit of the age / antiquity / a time in one's life, one's days (in college etc.)

use one thing for many purposes / work someone hard

to use one's head

Mongolia

secondhand goods shop