(i) = through, all over.

perrumpere = break through.
perspĭcēre = look through.

(ii) = thoroughly, to completion.

perdiscere = learn thoroughly.
perfungi = go through a duty, discharge.
permagnus = very large.

PRAE = in front.

(i) = (of place) before, in front.

praefĭcere = put at the head of.
praeses (sĕdeo) = guardian.

(ii) = (of time) before, too soon.

praediscere = learn beforehand.
praevĕnire = outstrip.

(iii) = before others, in comparison, greatly.