Can’t help without hearing the music examples or see the written examples!
Answer: rectative, aria, ground bass and triple.
Explanation:
The rhythm of the RECITATIVE is free, and the rhythm of the ARIA is more regular. The harmony of the aria is based on a chromatic GROUND BASS that descends by half step. The slow and melancholy TRIPLE meter expresses in the aria Dido's lamentation at Aeneas's departure.
