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

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

calculation / forecast

to calculate

use one thing for many purposes / work someone hard

to use one's head

everything

(colloquial) current boyfriend