"Last week he drew a picture"
Translation:Alichora picha wiki iliyopita
uliopita with noun classes 3, 11 and 14 and iliyopita with noun classes 4 and 9. It's just a verb form, so whether you'd use a verb starting with u- it's uliopita and with i- it's iliyopita.
Wiki iliyopita = last week (class 9) Mwezi uliopita = last month (class 3) Mwaka uliopita = last year (class 3)