前两个已经做了
The postman delivered a newspaper this morning
---A newspaper was delivered by the postman this morning
My mother gave me a present yesterday
---A present was given to me by my mother yesterday
The police have arrested the thief
---The thief has been arrested by the police.
He was typing a letter
---A letter was being typed by him.
如不明白请追问,要是满意请【采纳】
祝学习进步