refer to a hypothetical future situation: (Cicero) 'nor do I doubt that, if only the Senate still existed in the republic, one day a statue would be set up to this man in the forum.' As illustrated above, in an unreal conditional, the imperfect or pluperfect tense of the subjunctive in the protasis '(if' clause) remains unchanged, even after a primary tense verb. Past unreal events and situations An indirect question about an unreal past situation has the future participle plus the perfect subjunctive of : (Livy) 'tell us, Appius Claudius, what you would have done if you had been censor at that time?' After a historic introductory verb in an unreal conditional clause, the potential perfect subjunctive is usually still retained (contrary to the usual sequence of tenses rule): (Livy) 'nor was there any doubt that if it were possible for so few to manage everything at once, the enemy would have turned their backs' Occasionally, however, the subjunctive becomes pluperfect, but this is rare, and found only in Livy: (Livy) 'it occurred to them how impossible Etruria would have been, if anything had gone wrong in Samnium' 'Could have done' 'Could have done' can be used instead of 'would have done', since the two are close in meaning. So in an indirect question it is possible to use the perfect subjunctive with the present infinitive; (Cicero) 'you ask what more Plancius could/would have achieved, if he had been the son of Gnaeus Scipio' The perfect subjunctive is usually retained even in a historic context: (Livy) 'there was no doubt that if the delay had not intervened, the Carthaginian camp could/would have been captured on that day' Present subjunctive in historic sequence Just as in narrative, when writers often change from the perfect (or imperfect) to the historical present tense to make their writing more vivid, so in the same way the subjunctives in indirect speech sometimes use the two primary tenses (present and perfect) even when the context is past. This practice is known as . Usually if the introductory verb of indirect speech is in a primary tense, the subjunctive verbs are primary, while if it is historic, the subjunctive verbs are historic. However, even in the same sentence, a writer may switch between historic and primary tenses, as in the following example, in which (imperfect) is historic, despite the present tense introductory verb, but (present) and