We form it with be + participle. Be in the same tense as the sentence.
By + agent OMIT:
The agent is unkwnow/is not very important/don't want to name it.
1- if + present simple, will + inf.
2- if + past simple, would + inf.
3- if + past perfect, would have + past participle.
I WISH/IF ONLY
I wish + past simple present situation that we want to be diferent.
I wish + past perfect past situation that we want to be diferent.
I wish + would + infinitive to complain about a person.
agree + to + inf.
apologize + for + verb(ing)
refuse + to + inf
ask(sb) + if/wheter (how/where/why...)