The dragon was flying (fly) over the castle when he heard (hear) a girl crying.
The dragon was flying (fly) over the castle when he heard (hear) a girl crying.
→ Rồng đang bay (past continuous) thì nghe thấy tiếng khóc (past simple).
Dịch: Con rồng đang bay qua lâu đài thì nó nghe thấy một cô gái khóc.