The Conditional Mood

Form: the Conditional Mood is built with the help of the mood auxiliaries «should» for the first persons singular and plural and «would» for the second and third persons singular and plural + the Infinitive (Indefinite, Perfect, Continuous).

e.g. If he were here he would help us.

If I left home, I think I should be lonely.

If you had called on him, he would have come.

If she could, she would be staying with us at the moment.

Sometimes modal verbs «may», «might», «could» «can» are used in their suppositional meaning.

e.g. If she were younger, she could run faster.

If he knew the facts, he might tell us what to do.

Meaning: this form represents unreality of the action, impossibility of realization of which depends on the circumstances given in the subordinate clause. This form is mainly used in the principal clause of a complex sentence with a subordinate clause of unreal condition.

e.g. If I had not been busy yesterday, I should have come to see you.

Note 1: in everyday speech the auxiliary should is often replaced by the auxiliary would. And it is authentic to use a contracted form of both auxiliaries to avoid ambiguity:

e.g. If I had not been busy yesterday, I would have come to see you.

If I left home, I think I would be lonely.

If I had not been busy yesterday, I’d have come to see you.

If I left home, I think I’d be lonely.

Note 2: if the action (consequence) in the principal clause is referred to the present/ future/ no particular time, the so-called Present Conditional form is used that consists of the auxiliaries should/ would and the Indefinite/ Continuous Infinitive of a notional verb:

e.g. What would you do if you found a wallet in the street?

You wouldn’t be saying such nonsense, if you could understand gestures.

If the action (consequence) in the principal clause is referred to the past, the Past Conditional form is used that consists of the auxiliaries should/ would and the Perfect/ Perfect Continuous Infinitive of a notional verb:

e.g. What would you have done then if you had known that before?

You wouldn’t have been saying such nonsense, if you could have understood the gestures.

The Suppositional Mood

Form: the Suppositional Mood is built up with the help of the mood auxiliary «should» for all persons singular and plural + the Infinitive (Indefinite, Perfect, Continuous).

e.g. I insist that you should go there.

He insists that Mrs Smith should be present there.

It is impossible that he should have done so.

She fears lest they should come.

Meaning: this form is used to express necessity order, suggestion, supposition etc. It represents an action as problematic but not necessarily contradicting reality. The realization of the action may depend on certain circumstances which are not contrary to fact:

e.g. I insist that you should consult a doctor.

It means “I do not represent your consulting a doctor as an actual fact which will take place in the future but only as something that in my opinion you ought to do. The realization of the action depends on you.

The Suppositional Mood is used in many types of subordinate clauses, except subordinate clauses of unreal condition.