Ответ:
How long David has lived here?
David has lived here for 5 years.
He has lived here since 1988.
How long has he been here?
He has been here for 3 days
He has been here since May
How long has he known them?
He has known them for 3 years
He has known them since 1991
How long has David had them?
David has had them for 2 days
David has had them for ten years.