Would it be wrong to say:
"Η αράχνη είναι ζώο."
??? (without the "ένα")
(I ask because this is what I responded and it was marked as incorrect.)
I must have done over 100 of this statement and all have omitted the ενα so why is this one so different? Your answer that it is because it is ONE spider is totally illogical!
"Η αράχνη είναι ζώο." is one of the accepted translations. If your sentence was rejected there was an error but it was not due to the use of / not use of "ένα".
I keep mixing up ειμαι and ειναι.
It's OK, sometimes it's little things that keep tripping us up. You're at level 11, you're already doing great, keep at it! :)
I get weary of sometimes needing a ενα and sometimes not.