"I gave her a tomato."
Translation:Της έδωσα μία τομάτα.
It could not, because the short forms of pronouns always appear before the verb. (Exception: in an imperative/command, in which case they are right after the verb.)
So if you want to put the pronoun after the verb, you have to use the full form -- by itself for an accusative pronoun, and σε + full accusative pronoun instead of a short genitive pronoun.
For example, της έδωσα = έδωσα σ' αυτήν -- την είδα = είδα αυτήν.
But Δώσε της μια τομάτα for "Give her a tomato!".
"For example, της έδωσα = έδωσα σ' αυτήν -- την είδα = είδα αυτήν." But: "την είδα" uses "short" ACCUSATIVE pronoun (not genitive), doesn't it? At the moment I'm pretty confused about the genetive/accusative use combining with verbs. q.v.: https://www.duolingo.com/comment/23984622$comment_id=23985632
It depends on whether it's a direct or indirect object. In this case, ντομάτα is the direct object so it's in accusative, and αυτή (της) is the indirect object and it's in genitive. The indirect object could be found in accusative in this case, but it would need a preposition "Έδωσα σε αυτή μία ντομάτα"
Also, check D_..'s comment below :)
;) look what I encountered incidentally today: https://blogs.transparent.com/greek/untangling-the-greek-personal-pronouns/
Έδωσε is the third person singular (he /she gave), έδωσα is I gave.
While σε αυτή is not incorrect, usually the pronoun expressing the verb object goes before the verb in its weak form. What does this mean?
Use the strong pronoun form to give emphasis:
Δίνω αυτό σε αυτή - I give this (not something else) to her (not someone else)
Use the weak form to just say something:
Της δίνω το βιβλίο - I give her the book.
Της το δίνω - I give it to her.
Της δίνω αυτό - I give her this (emphasis on this, not something else)
Δίνω το βιβλίο σε αυτή - I give the book to her.
Using the weak form is the most common way of stating something, it's the base on which everything else is built to add emphasis. This is also true for verbs with one object:
Το θέλω - I want it. (weak)
Θέλω αυτό - I want this. (strong)