An active sentence that does not have an object cannot be made into the passive voice.

Active voice:   She cried. (The verb has no object, so you cannot make a passive sentence)

Active voice: An accident happened. (Again, no object, so you cannot form a passive sentence)

Intransitive verbs, verbs that never have an object, like be, die, happen, exist, appear can never be made into the passive voice. Only transitive verbs (enjoy, kill, catch, show) can be used in the passive voice. (Hint: They are called transitive because you can transfer an object to them
CHO MIK 10 ỂM NHA