Condition sentences can be divided into three types: Type I refers to real conditional sentences that use the future tense. Type II refers to unreal conditional sentences that use the past tense and imply something contrary to fact. Type III refers to unreal conditional sentences that use the past perfect tense to talk about a hypothetical situation in the past.

1. CONDITIONAL SENTENCES.
Condition Subordinate
clause
Principal clause Translation
Type I (real)
Будущее
If I have more
time,
Present
Simple/Continuou
s
I’ll do it.
Will + inf
Реально, при
выполнении первого
условия в будущем,
второе условие
выполнимо.
Type II
(unreal)
Настоящее
If I had more time,
Past
Simple/Continuou
s
I would do it.
Would/could/might +
inf
Нереально, появляется
сослагательное
наклонение (частица
БЫ).
Type III
(unreal)
Прошедшее
If I had had more
time yesterday,
Past Perfect
I would have done it.
Would/could/might +
have + Participle II
Нереально, действие
произошло в прошлом.
Условие, при котором
действие могло бы быть
выполнено, не было
реализовано. НИЧЕГО
вернуть уже НЕЛЬЗЯ!

2. Type I – If (common),
In case (в случае если) – In case I don’t find her at home, I’ll
leave her a note. Provided (при условии) – We’ll finish the
work on time provided you send all the necessary materials.
Unless = if not (если…не) – I’ll come in time unless I am
detained at the University.
Type II, III – If (common)
Suppose (предположим) – Suppose he wrote to you, would you
answer?
But for (если бы не….) - But for the rain we would go down to
the country.
If it were not for your help, I wouldn’t be able to get such good
results.
If it hadn’t been for me, they would have never found the place.