The book my student's using says when changing from Active to passive, the verb has to be changed to V3 plus a form of "to be."
Sure, this seems fine for:
Bob drank the soda. ----> The soda was drunk by Bob.
The doctor saw the patient. ----> The patient was seen by the doctor.
You must sleep eight hours every night.
Every night you must get eight hours of sleep (sounds correct to me)
If the student follows the rule in the book, then it would be something like-
Eight hours of sleep must be slept every night. (?)
Past Participle is sometimes called Verb 3
and I also think that there's a number of verbs that shouldn't be twisted into passive....but this student's teacher has put that particular example in a worksheet for the class
'Sleep' is intransitive, and generally you don't make intransitive verbs passive.
"He ran to the shop." -> "The shop was run to by him." Possible, but silly.
"He snores" -> "Snores are made/emitted/performed by him"?
Yes, that's it! Thank you. I may be teaching that level next session so I better get myself schooled with intransitive verbs...