"I do not eat turtles."
Translation:Jeg spiser ikke skilpadder.
'ei' is an alternative form of 'ikke', which is almost never used. You should always use 'ikke'.
Why is it wrong to say "jeg spiser skilpadder ikke" but it's correct to say "jeg elsker henne ikke"?
There are different rules for regular nouns and personal pronouns in this case.
"Ikke" comes before regular nouns, but with personal pronouns you have the option of placing it either before or after. Beware that this can alter the meaning of the sentence:
Jeg elsker ikke henne = I do not love HER (but someone else)
Jeg elsker henne ikke = I do not love her (neutral) -or- I do not LOVE her (but like her a lot)
It's the third time this sentence is in a test, finally I'm learning something useful :D