Some say that Brazilian Portuguese is one of the most difficult languages.
It’s not.
The pronunciation is pretty tough to learn, though.

(from Semantica Advanced Dialogs)
The grammar is very consistent and things like the past participle is much easier than the english rules.
Let’s compare:
eaten, finished, found, gone, known, brought
Insane. If there is a set of rules for learning these, I don’t even want to hear about it.
Now in portuguese:
comido/a
terminado/a
achado/a
conhecido/a
trazido/a
As you can, the past participle is formed by taking removing the AR, ER, IR ending and replacing it with ado for AR verbs, ido for ER or IR verbs. *** and of course, you must use an “a” instead of an “o” if the subject is feminine.
Yes, there are irregulars as well.
But the hell with them, let’s look at some great examples of the particípio do passado in action!
O arroz está cozido.
O carro está estacionado.
A carta já foi enviada. *** notice the subject is feminine here!
Ela tem estudado todos os dias.
O prédio foi vendido.
Ele foi amado por todos.
* one of the most obvious examples of the subject-gender agreement that has to happen is the verb obrigar.
A man always say “obrigado” .. the woman always says “obrigada” (if she doesn’t check for facial hair)
Maktub, particípio passado do verbo Kitab, é a expressão característica do fatalismo muçulmano, maktub significa: “estava escrito” ou melhor, “tinha que acontecer”.. – Oriente