UPPER INTERMEDIATE - GRAMMAR 1 (page 1)
can have passive sentences in many different tenses.
snake was eaten.
... and so on.
In a passive sentence we are not so interested in who or what did the action (who ate the snake). We are more interested in the result.
passive is formed by putting the object of the verb before the verb. We
can move the subject of the verb to the end or we can delete it.
The men ate the snake.
We use an auxilliary and a past participle. Click here for a list of common past participles.