I've just finished lesson 2.6 of Paralee's course, on the Preterit tense. I think I've got the hang of it, but this was one thing I couldn't find a reason for: "vi" has no tilde but "subí" does. Is one of them irregular?
And since I'm asking I might as well inquire as to what the last sentence meant:
"Subisteis las escaleras en lugar de usar el ascensor."
You all climbed the stairs..in place...to use the lift. Is that like "instead of using the lift"?