Tenses in Latin are divided into two groups.
Primary tenses:
Indicative
Subjunctive
Present
Present
Future
Perfect
Future Perfect
And Historic tenses:
Indicative
Subjunctive
Imperfect
Imperfect
Perfect
Pluperfect
Pluperfect
When we have a dependent clause with its verb in the subjunctive, the tense of the subjunctive is determined by the tense of the principal verb. Primary tenses follow primary, and historic tenses follow historic. The imperative is always followed by a primary tense.