6.2.3 Second conditional
if + past subjunctive | would + infinitive (simple or continuous)
The second conditional can describe an unreal situation with reference to the present. We imagine a hypothetical situation which contrasts with reality:
If I knew the answer, I'd tell you.
Here If I knew the answer means that I don't know the answer.
In the if-clause, we use the past subjunctive form of the verb, which is identical to the past simple tense except in the case of the verb be. Traditionally, the past subjunctive form of be is were for all persons including the first and third person singular. However, nowadays I/he/she/it was is more common, while were is mainly used in formal styles and in the set phrase if I were you:
If I lived by the sea, I would be lying on the beach right now.
If he was/were taller, he would make a good basketball player.
If I were you, I'd stop smoking.
The second conditional can also express a theoretically possible but unlikely future situation. In the following examples, the conditions in the if-clause are possible but are not likely to be fulfilled:
If the Third World War broke out, it would probably mean the end of humankind.
If you missed the 6 o'clock train, you wouldn't get here before 7.
If I lost my job, I would be in serious trouble.
Compare the first and second conditionals when they refer to possible future actions:
If you miss the 6 o'clock train, you won't get here before 7. (first conditional, the condition is probable, you may miss the train)
If you missed the 6 o'clock train, you wouldn't get here before 7. (second conditional, the condition is possible but unlikely, you probably won't miss the train)
Past continuous subjunctive in the second conditional
The past continuous subjunctive can be used in the if-clause of a sentence in the second conditional to express an unreal action in the present which is imagined as continuous:
If it wasn't raining, we would have lunch outside. (it is raining)
If we were staying at the other hotel, we wouldn't have such a nice view of the river. (we are not staying at the other hotel)
If the kids weren't shouting all the time, perhaps I wouldn't feel so stressed. (the kids are shouting all the time)
Modals in the second conditional
Main clause
We can use modals other than would in the main clause of a sentence in the second conditional:
If no one was late, we could start the meeting on time. (ability)
If you asked George, he might be able to help you. (possibility)
If-clause
We can use could in the if-clause to express ability, possibility or permission:
I'd go to the beach with you if I could swim. (ability)
If you could be a famous person, who would you be? (possibility)
I wouldn't go to bars if people could smoke inside. (permission)