(onomatopoeia) tap tap, (soft) knock knock / progressing steadily and smoothly

nearly the same, almost equal / break-even, neither profitable nor costly

knock-knock (knocking sound)

a revolving door

knock (abrupt rapping sound) / (baseball) fungo

to knock / to press down on the rear end of a mechanical pencil and dispense lead

Western-style door

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