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)

Were to in the if-clause makes the condition even less likely:

If he were to propose to you now, what would you say?

We can use would in the if-clause to express requests. Sometimes, the main clause is omitted:

If you'd just fill in this form, please.