кай: when
Онҳо кай мераванд?
When are they leaving?
Ин кай рӯй медиҳад?
When will this happen?
Кай Туро гурусна дидему хӯрок додем?
When did we see you hungry and feed you?
Bonus:
то кай: until when, how long
кайҳо: long ago
Resources for learning the Tajik language
