Open the brackets passive voice 1 this fact (not to mention) In his last speech 2. The story already (to forget) by them

1). This fact was not mentioned in his last speech.

Past Simple passive voice, negative form.

"to be" in the negative form + Participle 2.

2). The story has already been forgotten by them.

Present Perfect passive voice, affirmative form.

"have/has" been + Participle 2. "Already" goes in the middle of the predicate, after "has".