sum and possum

[spqr]

I have difficulty distinguishing between the imperfect and perfect conjugations of these two words when translating from Latin to English. Any suggestions or pointers? Thanks, Paul

[Sigma]

Well, the perfect of possum always has a -tu- in it, while the imperfect never does:
possum, potes, potest, possumus, potestis, possunt
potui, potuisti, potuit, potuimus, potuitis, potuerunt

For sum, it's even easier because the perfect conjugations of sum all begin with f-, while this never happens in the imperfect:
sum, es, est, sumus, estis, sunt
fui, fuisti, fuit, fuimus, fuistis, fuerunt

[Sceptra Tenens]

I think he means that he has difficulty differentiating the signification of the two aspects.

The imperfect is used for something ongoing at the time of the narrative; puer erat for "he was a boy", showing that he was not only a boy at the time, but also before and after.

The perfect is for something completed by or during the time of the narrative; puer fuit in conclavi for "the boy was in the room", showing that he had been in the room for a while, but came out at some time within the scope of the narrative.

[pmda]

Sigma your 2nd pers. singular looks wrong. potuisti and fuisti are 2nd pers. sing. for these two verbs.

I'm not sure why these two words in particular should cause this problem.

Impf. poteram, poteras, poterat, poteramus, poteratis, poterant.
Meaning. I...you...he...we...they... was/were able (over a period of time).

Perf. potui, potuisti, potuit, potuimus, potustis, potuerunt / ere.
Meaning. I...you...he...we...they... was/were able (at a particular instance (time) now ended)

Impf. eram, eras, erat, eramus, eratis, erant.
Meaning: Impf. I...you...he...we...they... was/were (over a period of time)

Perf. fui, fuisti, fuit, fuimus, fuistis, fuerunt / ere
Meaning. I...you...he...we...they... was/were (at a particular instance (time) now ended)

[Sigma]

Sigma your 2nd pers. singular looks wrong. potuisti and fuisti are 2nd pers. sing. for these two verbs.

Yes, thank you.