Am I right in getting the impression that ‘eram’ and ‘fui’ are more or less interchangeable? The distinction between perfect and imperfect does not seem to apply to this verb as it does to others. When I’m doing composition exercises all I can do is guess which one I will find when I look in the key.
You’ll have to post examples so we can check them out on a case-by-case basis. As far as I know the same explanations for the imperfect as any other verb hold for eram. But the difference in aspect can be subtle and sometimes arbitrary, it’s true. There are certainly differences when you’re using esse with a past participle (amatus sum vs. amatus eram vs. amatus fui).
It seems for most purposes eram is employed most of the time, but here are some examples and counter-examples that I’ve collected from N&H:
FUI
Legibus a nobis parendum fuit =We had to obey the laws.
Non hoc agendum fuit=This should not have been done.
Crasso in Asiam non eundum fuit=Crassus ought not to have gone to Asia
ERAM
Omnia Caesari simul agenda erant=Caesar had to do everything at the same time
Socii eis adiuvandi erant=They ought to have helped their allies.
FUI
Haec negligentia ei dedecori fuit.= This negligence has brought disgrace upon him.
Bono fuit Romanis reges expellere= It was to the advantage of the Romans to banish the kings.
Haec victoria saluti fuit civitati.=This victory was the salvation of the state.
Locus ipse magno gallis praesidio fuit=The position itself was a great help to the Gauls.
ERAM
Poena causae mortis ei erat=His punishment was the cause of his death
Laudi mihi erat quod domum tutus advenisti=It was to my credit that you got home safely
Odio erat omnibus bonis=He was an object of hatred to all good men.
FUI
Diu ferociter pugnatum est, etsi numero hostibus multo inferiores fuimus=The battle raged fiercely for a long time, although we were greatly inferior to the enemy in numbers.
ERAM
Etsi hostibus numero inferiores erant, locum summa constantia tenebant=Although they were inferior to the enemy in numbers, they held their ground resolutely.
I’m afraid I can’t see much of a pattern here.
Well, maybe translating into English they look more interchangeable. Sometimes I think they are, but other times they aren’t. Like past paticiples and more. I am Portuguese so I translate eram to era and fui to fui. They change the meaning in Portuguese if I change them. When, for example, I talk about the past comparing something with the present I should use eram. Fui is for usage of past actions completed. Not of a great help I guess…
The imprefect shows continuing action: to preform a minor correction on one of your sentances: "Etsi hostibus numero inferiores erant, locum summa constantia tenebant=Although they were inferior to the enemy in numbers, they held their ground resolutely. " The translation more literally would be “Although they were being fewer in number than the enemy, they were holding their ground resolutly.”