Using the Imperfect Subjunctive
Portuguese uses the Subjunctive mood to indicate something is uncertain to happen or to have occurred. There are 3 different degrees of uncertainty: (1) extremely unlikely, (2) plausible, (3) likely.
The Imperfect Subjunctive is used for case (1): actions that are extremely unlikely to happen or to have happened.
Whenever the sentence conveys: were to something, USE THIS TENSE. And it's easy to hear when someone is using it because you'll hear the pleasant esse or asse attached to the verb. This is an easy conjugation to speak as well since you really only need the eu, você, ele, ela forms and they are all the same!
It's all asse or esse!
|were to know||eu, você, ele, ela, a gente soub||esse|
|were to have||eu, você, ele, ela, a gente tiv||esse|
|were to say||eu, você, ele, ela, a gente fal||asse|
So, for COMER: simple past »: comeu » » comesse
For an irregular verb like SABER it's: simple past »: soube » » soubesse
Forming the Imperfect Subjunctive
-ar imperfect subjunctive regular verbs
|I were to say||eu fala||sse|
|you were to say||você fala||sse|
|we were to say||nós falá||ssemos|
|they were to say||eles fala||ssem|
-er imperfect subjunctive regular verbs
|I were to lose||eu perde||sse|
|you were to lose||você perde||sse|
|we were to lose||nós perdê||ssemos|
|they were to lose||eles perde||ssem|
-ir imperfect subjunctive regular verbs
|I were to go out||eu saí||sse|
|you were to go out||você saí||sse|
|we were to go out||nós saí||ssemos|
|they were to go out||eles saí||ssem|
Examples of the Imperfect Subjunctive
In this example, it's not clear if it's saying that I didn't win therefore I didn't buy the car or, that if someday I win, I will buy the car. Usually, the context is enough to clarify. But, let's rewrite the sentence it and be crystal clear that we're talking about the past:
Can we place the context in the future? Podemos!
By saying vou comprar... it removes all ambiguity. You're speaking about a hypothetical future event. And that's what the Subjunctive Mood is all about. This form, the Imperfect Subjunctive is the most uncertain, most unlikely, most doubtful version of the three forms: the Present Subjunctive, the Future Subjunctive, and this the Imperfect Subjunctive. This one is labled the IMPERFECT subjuntive because it's just that: not very clear if it's talknig about action in the past, presetn or future. Just use it when things are very, very improbable.
You can also use it when telling a story about something in the past that includes something that did not happen. This is pretty confusing! Let's look at an example:
In this case, this is something that did not happen. I did not speak with the manager.
Let's stick to some more common examples:
Notice also how in all of these examples, the subjunctive verb is followed up with one in the Conditional tense? That's because this tense is absolutely PERFECT for saying things like, IF such and such were to happen it WOULD BE whatever. This is the classic usage and always triggers this tense!
I remember it like this:
IF SOMETHING WERE, THEN SOMETHING WOULD.
I've posted some good examples of the Imperfect Subjunctive together with the Conditional tense.