As we saw in the discussion of the Present Subjunctive, under normal circumstances, the subjunctive has to do with elements of doubt, tentativeness, uncertainty, and vagueness. In the section on the Past Subjunctive, this is explained in greater detail.
The perfect subjunctive is constructed by adding the present subjunctive of the verb “to be” (that is, باشـ) to the past participle. Just like the past participle, the stress invariably stays on the last syllable of the participle of simple, complex, or compound verbs. The negative is constructed by adding the [na-] prefix to the participle. This particular subjunctive construction corresponds to the English, “must have …, should have…, could have…, etc.,” representing things like necessity, possibility, desire, or wish.
As is always the case with the subjunctive, this verb also comes prior to a main verb:
باید او را دیده باشید
bāyad u rā dide bāšid
“You must have seen her/him.”
بهتر است (که) آن کار را نکرده باشد
behtar ast (ke) ān kār rā nakarde bāšad
“He’d better not have done that.”
ممکن نیست (که) آنجا را دیده باشند
momken nist (ke) ānjā rā dide bāšand
“It isn’t possible for them to have seen that place.”
نمی توانند آنجا را دیده باشند
nami tavānand ānjā rā dide bāšand
“They can’t have seen that place.”
Now compare the following tenses:
Present:
می توانی امروز آن را ببینی
mi tavāni emruz ān rā bebini
“You can/may see it today.”
Past:
دیروز می توانستی آن را ببینی
diruz mi tavānesti ān rā bebini
“You could see it yesterday.”
Future:
می توانی فردا آن را ببینی
mi tavāni fardā ān rā bebini
“You can/may see it tomorrow.”
Perfect:
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