The following modal verbs can be used in conditional sentences in the Subjunctive mood:

  • Could

    If the action refers to the past could is followed by the Perfect Infinitive. Could - expresses possibility.

    But for the bad weather we could go to the country.
    Несмотря на плохую погоду, мы могли бы поехать загород.

    If I had had money about me yesterday, I could have bought this book.
    Если бы у меня вчера были с собой деньги, я мог бы купить эту книгу.

  • Might

    Might expresses possibility (could is more common here) or somebody's supposition.

    If he asked me for help, I might help him.
    Если бы он попросил меня о помощи, я бы мог помочь ему.

    If Nick had proposed to me then, I might have married him.
    Если бы Ник тогда предложил мне, я возможно вышла бы за него.

    If the action refers to the past might is followed by the Perfect Infinitive.

  • To have

    To have expresses necessity.

    If I weren't ill, I should have to go on this business trip.
    Если бы я сейчас не был болен, мне пришлось бы поехать в эту командировку.

    If had not stayed in Switzerland, I should have had to take part in this project.
    Если бы я не задержался в Швейцарии, мне пришлось бы принять участие в этом проекте.

  • Would

    Would expresses wish or resolution to perform an action.

    If you would join my group, I would give you a very interesting job.
    Если бы ты пожелал перейти в мою группу, я непременно поручил бы тебе очень интересную работу.