Came across these in my practice on the reverse Spanish tree
No estás lanzado el balon lo suficientemente fuerte
Tu automóvil no es lo suficientemente grande o sí
Yo no pude correr lo suficientemente rapido
Yo no estudié lo suficiente
I hadn't come across the lo suficiente/suficientemente usage before and I didn't use the "lo" when translating into Spanish. Duolingo accepted my answers. I did some digging later and came across this explanation
https://www.espanolavanzado.com/uso-de- ... ientemente
My question is whether in the "Lo" in the lo suficiente/suficientemente usage is optional? Is it like the redundant IO pronoun that can sometimes be dropped but that native speakers rarely do? To me this isn't an intuitive construction to remember and unlike the redundant IO pronoun I don't know that I'll get much practice to internalize it.