Someone has prepared a meal for you.改为被动语态,省略(someone)

1，Someone has prepared a meal for you.
A meal has been prepared for you.
2,Someone will translate the book into English
The book will be translated into English
3,Someone must send a telegraph to him
A telegraph must be sent to him.
4,Someone had put out the fire before the fire brigade arrived
The fire had been put out before the fire brigade arrived
5,Someone gave the cat some milk to drink
The cat was given some milk to drink.

1 A meal has been prepared for you by someone.
2 The book will be translated into English by someone.
3 A telegram must be sent to him by someone.
4. The fire has been put out by someone before the fire brigade arrived.
5. Some milk was given to the cat to drink by someone.