Unchangeable tenses

[shuja87]

What are the tenses which cannot be changed into passive? Or, in other words, what are some tenses which have no passive form?

[Philly]

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I think it is possible to change any tense to passive. Some tenses just tend to be used much less often in the passive than others.
The "cannot be done" idea comes into play if you attempt to change an intransitive verb to a passive form.