Spanish language Q&A Forum

I see in this lesson that when the subject is the same, we should be using the infinitive. I need to work on that!

Is it ever a  “tolerable” error among native speakers to commit this mistake when using a colloquial register? I frequently want to say things like “Dudo que (yo) pueda hacerlo para viernes” instead of “poder hacerlo.” I know you’re here to teach us the right way!! Just curious as to “how” wrong it is.

Why is the (se) in parentheses in the title of the lesson? Every example is reflexive. Would one ever use a non-reflexive quedar in this context? (If not, it seems like the parentheses aren't needed, no?)