SÍ and DO compared

Emphatic SÍ and DO.

¿Quieres ir? No. Y tú, ¿quieres ir? Yo sí. Yo sí quiero ir. // Do you want to go. No. And you, do you want to go? I do. I do want to go. //
Yo no le comprendo. Yo sí le comprendo. //
I don´t understand him. I do understand him. //

Ella sí me quiere. She does love me. // The sí will remain in Spanish but will turn into will, have, did... in English: Sí se lo diré. I will tell her. (stress will) //
Yo sí la invité a la fiesta. I did invite her to the party. //
Ellos sí han comprado la casa. They have bought the house. (stress have)