the passive vois

we use "the passive" to describe a process when it's not important to kno who did the action.
e.g. we wereall invinted to the concert...
.we form the passive like this :object+be+past participle+agent(by+noun)
e.g.penicillin(o)wasdiscovered(pp)by a. fleming.
NOTE:
the form the auxiliary 'be'in the passive voice is the same as the form of the verb in the active voice.
e.g. a.fleming discovered penicillin.(past simple)
penicillin was discovered by A.fleming(past simple)

thanks

شكرا