The Grammaring Guide to English Grammar with Exercises

Less likely conditions

First conditional

In the first conditional, happen to and should can be used in the if-clause to express that something is possible but not very likely:

If you

happen to see

Kate, say hi from me.

If you

should see

Kate, say hi from me.

Second conditional

In the second conditional, we can use were to for unlikelihood:

If he

were to propose

to you now, what would you say?

Third conditional

Here were to + perfect infinitive expresses an imaginary past action which was very unlikely:

If he

were to have asked

me, I would have said yes.