Сделать из active voice в passive voice we also invite them to attend school meetings last year we selebrated the 66th anniversary of the victory it is unfair ,but every year we see fewer and fewer veterans

They are also invited to attend school meetings.

Last year the 66th anniversary of the Victory was celebrated (by us).

It is unfair, but every year fewer and fewer veterans are seen.

1) they are invited to the attend school meetings by us.
2) last year the 66th anniversary of the victory was celebrated by us.
3) it's unfair, but every year fewer and fewer veterans are seen by us.