do native speakers tend to say 'sé' or 'yo sé'? I know you don't need yo with every verb, and I usually don't, but I feel weird just saying sé. muchas gracias <3
If you want to say “I know” as in English, as a quick response about something that someone said. In Spanish we usually say:
Lo sé: I know it
Ya sé: “I know, right?” or “I know (you don’t have to tell me again)” depending on the context and the intonation.
If we say Yo sé then we need a complement:
Yo sé que tienes mucho trabajo. - I know you have a lot of work.
As you said it right, we don’t always use the pronoun “yo”, only if it’s obvious that we are talking about ourselves, for example in these other expressions:
No lo sé / No sé: I don’t know
Lo sabía: I knew it
Ya lo sabía: I knew it (already; even before you told me)
No lo sabía: I didn’t know
But we need “yo” when more than two people are talking, or when we talk about someone else and then we change the topic about ourselves.
[In a classroom]
– ¿Quién sabe cuál es la capital de Argentina? - Who knows the capital of Argentina?
– ¡Yo sé! - I know!
In this case we have to use “yo” because among all the other students it’s me who knows the answer.
[In a group of 3 friends]
A: ¿Cuando va a ser la reunión? - When is the meeting going to be?
B: Yo no sé. - I don’t know
C: Yo tampoco. - Me either
In this case we also need “yo” because speaker A is talking to two people. So speaker B is like “I don’t know about my friend, but as for me, I don’t know”.
And we always use “yo” when we say “yo también” (me too) or “yo tampoco” (me either).
[When we change the topic]:
Eso me dijo, pero yo sé que me estaba mintiendo.
That’s what he told me, but I know he was lying to me.
In this case, we need “yo” because in the first part of the sentence we talk about him, and in the second part we talk about us.
Todos iban vestidos de blanco, pero yo no sabía y fui con un vestido rojo.
Everybody went dressed in white, but I didn’t know and I went in a red dress.
In this case we also need “yo” because the first part of the sentence talks about everybody else and the second part talks about us.
We can also use “yo” to make more emphasis on what we know. Usually when we comfort someone, or we give an advice, or we make an excuse, or we ask for a favor.
Yo sé que tienes mucho trabajo, pero necesito que me ayudes.
I know you have a lot of work, but I need you to help me.
Yo sé que esta etapa es muy difícil, pero también sé que eres muy inteligente y puedes lograrlo.
I know this phase is very difficult, but I also know you are very intelligent and you can make it.
Yo sé que es importante, pero lo olvidé por completo.
I know it’s important, but I completely forgot.
I hope this was helpful! :)