Answer:
The sentence is:
"Nosotros sabemos la verdad."
Where the verb is "sabemos" and the subject is "Nosotros".
We want to change the conjugation from present to preterite (past )
The perfect tense would be: Supimos, and the sentence:
Nosotros no supimos la verdad.
Where the action is already ben ended, which means that they in the past did not know the truth, but now they do.
The imperfect preterite would be:
"Nosotros no sabiamos la verdad"
where the action may or may not ben ended.
