These flowers have been watered by my father since this morning

` -> ` Ta có cấu trúc câu bị động thì HTHT :
` - ` S + have / has + been + VPII + by + O

` DHNB ` : Since this morning

My father has watered these flowers since this morning (HTHT)

→ These flowers has been watered by my father since this morning.

→ DHNB: Since this morning → HTHT

Chuyển active sang passive thì HTHT.

Active: S + has/have + Vpp + O

Passvie: S + have/has + been + Vpp + (by sb) +....