Translate the verb. Write the base form, past simple and past participle 1. be able to be able)​

The door is closed. Дверь закрыта.
• The song was sung. Песня была спета.  

2. Неизвестно, кто

Субъект, совершивший действие, неизвестен.

• The crime was committed. Было совершено преступление.
• It was stolen. Это было украдено. 

3. Неинтересно, кто

Субъект, совершивший действие, неинтересен - речь совсем не о нём.

• The house will be painted blue. Дом будет покрашен в голубой цвет.

4. Вежливый отказ

• Your request was rejected. Ваша была отклонена.
  Вместо: я отклонил вашу

Как всё-таки упомянуть того,  кто совершил действие? Взять этого субъекта и поставить его в конец предложения, на место дополнения:
• The patient was seen by a doctor. Пациент был осмотрен доктором.
• The order was finally made by ​​them. Заказ был, наконец, выполнен ими.

by выражает творительный падеж
кем? - мной, им: by me, by him

Правила разобраны. Примеры приведены. Знай - выбирай, в активе выразиться или в пассиве.

 актив 
  He
 
  loves
 
  her
    Он  любит  её   подлежащее  сказуемое    дополнение   или пассив 
  She
 
  is loved
 
  by him
    Она   любима  им   подлежащее    сказуемое  дополнение

Если выбран пассив, значит, пригодится третья форма неправильных глаголов.

• Everything will be done. Всё будет сделано.
• The job is done. Работа сделана. 

do - did - done.  делать

• The house will be built next year. Дом будет построен в следующем году.

build - built -built.  строить

С правильными проще: invite - invited.

• I was invited. Я был приглашён.

как то так 

1 If I see him I (will give) him a lift.
2 The table will collapse if you (stand) on it.
3 If he (eats) all that he will be ill.
4 If I find your passport I (will telephone) you at once.
5 The police (will arrest) him if they catch him.
6 If he (reads) in bad light he will ruin his eyes.
7 Someone (will steal) your car if you leave it unlocked.
8 What will happen if my parachute (does not open)?
9 If he (washes) my car I'll give him £10.
10 If she (needs) a radio she can borrow mine.
1 If I had a typewriter I (would type) it myself.
2 If I (knew) his address I'd give it to you.
3 He (would look) a lot better if he shaved more often.
4 If you (played) for lower stakes you wouldn't lose so much.
5 If he worked more slowly he (would not make) so many
mistakes.
6 I shouldn't drink that wine if I (were) you.
7 More tourists would come to this country if it (had) a
better climate.
8 If I were sent to prison would you (visit) me?
9 If someone (gave) you a helicopter what would you do
with it?
10 I (would buy) shares in that company if I had some money.
1 If I had known that you were in hospital I (would have visited) you.
2 The ground was very soft. But for that, my horse (would have won).
3 If you (had arrived) ten minutes earlier you would have got a
seat.
4 You would have seen my garden at its best if you (had been) here last week.
5 But for his quickness I (would have been been) killed.
6 I shouldn't have believed it if I (had not seen) it with my own
eyes.
7 If he had slipped he (would have fallen) 500 metres.
8 If he had asked you, would you have (accepted)?
9 If I (had had) a map I would have been all right.
10 If I (had known) that you were coming I'd have baked a cake.