The Portuguese preposition de shows up everywhere. As you know, I DISLIKE digging in to linguistics unless it's necessary to move forward / to understand something. *I don't actually dislike studying the nature, structure, and variation of language, including phonetics, phonology, morphology, syntax, semantics, sociolinguistics, and pragmatics (!!!). It's that it doesn't really help you get to fluency. In fact, knowing too much about the grammar structure of Portuguese can actually slow you down. It's just too much to take in and is best enjoyed over a caipirinha and some Bossa Nova.
The Semantica approach is always to make the point with examples.
The Portuguese preposition de can change the meaning of the sentence.
One very useful way that de can be used is to express: BY.
de = BY
Let's go by car. »
Vamos de carro.
You're literally saying: Let's go of car.
She's going by train. » Ela vai de trem.
I'm going by bus. » Eu vou de ônibus.
*Note that in English you could tanslate these in various way: I'm going by bus OR, I'm going to take the bus. If you wanted to say to take rather than, by this becomes: Eu vou pegar o ônibus.
de = TO WEAR
Watch how de can be used when talking about what to wear(!)
I'm going in a skirt. »
Eu vou de saia.
You're literally saying: I'm going of skirt.
I'm going in tennis shoes. » Eu vou de tênis.
Can I wear shorts? » Posso ir de shorts?
Verbs that usually combine with de
There are several verbs that you almost always see together with de or, that have to be used with de by LAW!
GOSTAR + de
You'll (almost) never see GOSTAR without a de. It's the law. I understand it like this: When you like something, you like of something.
Eu gosto de você. » I like you.
If there's an article after the de they combine (contract): Você gostou do filme? » Did you like the movie?
*The only way you can avoid using the de is to speak super-succinctly:
PRECISAR + de
When you need something, you need of something:
Eu preciso de dinheiro.
» I need money.
This is not a LAW like GOSTAR de is. When you use PRECISAR with another verb the de is not required: Eu preciso ganhar dinheiro. » I need to earn money.
More about PRECISAR.
ACABAR + de
ACABAR means to finish, to end. Without a de, it's used to say things like:
Minha paciência acabou.
» My patience is up.
When you include the de it takes the meaning of, "to have just" : Ela acabou de chegar. » She just arrived.
More about ACABAR.
MUDAR means to change. Using it without a de you can say things like:
Mas agora tudo mudou.
» But now, everything has changed.
Using it with the de you can say for example: Vamos mudar de assunto. » Let's change the subject.
Ela mudou de ideia. » She changed he mind.
More about MUDAR.
TROCAR + de
There are plenty of others such as TROCAR that you also see used together with de.
Preciso trocar de roupa. » I need to change clothes.
The last one I'm going to present here is ESQUECER.
Não vou esquecer de comprar pão. » I'm not going to forget to buy bread.
I'm fascinated by the way DE can be used together with verbs in the infinitive to say things I that are not at all intuitive! Freshen up your caipirinha and step into this all at your own risk.