Learn Italian: Dubitavo che distruggessero tutta la galassia. - I doubted that they would destroy the whole galaxy.

The main verb dubitavo (I doubted) expresses doubt, which triggers the subjunctive mood. Because dubitavo is in a past tense, the dependent verb shifts into the imperfect subjunctive to match the timeframe.

How do you form the imperfect subjunctive of an -ere verb like distruggere?

You take the infinitive distruggere, drop the -ere, and add the appropriate imperfect subjunctive ending. For the third-person plural (loro) form, that ending is -essero, giving us distruggessero. That double 's' is the trademark of the imperfect subjunctive!

The English translation says 'would destroy.' Why not use the conditional tense in Italian?

While English often uses 'would' for hypothetical ideas in the past, Italian grammar strictly requires the subjunctive after expressions of doubt like dubitare che. You cannot use the conditional here, even if the English translation sounds like it.

Why do we need the article la in tutta la galassia?

In Italian, when tutto or tutta means 'the whole' or 'all of the,' it must be followed by a definite article before the noun. Therefore, 'the whole galaxy' has to be constructed as tutta la galassia, not just tutta galassia.