As pointed out earlier, whenever the agent or the doer of the action expressed by a verb is being mentioned in the passive form, it is usually preceded by the preposition ‘by’ as in: John ate the food/ The food was eaten by John.
However, some passive forms cannot take the preposition ‘by’, especially when they involve materials used and not the agent as in: Dust covered the shelf/ The shelf was covered with dust. Oil filled the bucket/ The bucket was filled with oil.
With the use of phrasal verbs in structure, the passive forms take peculiar shapes. Whenever a verb + preposition + object combination is put into passive, the preposition after the verb will remain just immediately after the verb as in: The management should send for Dr Ibrahim/ Dr Ibrahim should be sent for.
She blew out the flame/ The flame was blown out.
Have a great week ahead!
