"I do not remember what I have done."

Translation: Δεν θυμάμαι τι έχω κάνει.

[ZacTheShave]

Γιατι δεν είναι 'Κάνω';

[mizinamo]

Because it's "what I have done", not "what I do".

Or if you were expecting τι έχω κάνω: because it's "what I have done", not "what I have do".

With έχω as a helping verb to form the perfect, you need the απαρέμφατο form of the meaning verb, which looks like the third person singular (he/she/it) aorist subjunctive (the form used after να or θα). "He will do" is θα κάνει and so κάνει is the form you use in perfect and pluperfect statements.

[Jimbo236]

What about Δεν θυμάμαι τι έκανα? It is wrong because of the purpose of this exercise or the meaning is different

[Niko837328]

It an instance where the difference in meaning is slight but important given the exercise. It's the difference between the English sentences:
I don't remember what I did. (Δεν θυμάμαι τι έκανα.)
And
I don't remember what I have done. (Δεν θυμάμαι τι έχω κάνει.)

[Bego705511]

"δεν θυμαμαι τι εγω εχω κανει" is not ok?

[fazulakis]

γιατί "δεν θυμάμαι ότι έχω κάνει"; ευχαριστώ.

[troll1995]

That would mean " I don't remember that I have done" unless you mean ό,τι in which case it would mean "I don't remember whatever I have done".

[Bohuslav1]

Can you not use "ό,τι" here?

[mizinamo]

That would mean "whatever" rather than simply "what".

[chari288242]

"Τι έχω κάνει, δεν θυμάμαι" δεν μπορεί;

[troll1995]

With the comma, it is translated as "what have I done, I don't remember" which is not the same syntax at all. Without the comma τι έχω κάνει δεν θυμάμαι It is correct. It is one of the many many cases that in greek the syntax is flexible and the words can be moved around without changing the meaning. Because it would be impossible to accept all possible syntaxes in all sentences, it is better to stay close to the original sentence's syntax to make sure that those answer is accepted.

[Nathalie975642]

Is it wrong to add έγω to the end of the answer?

[G.Georgopoulos]

It is correct. I've added it, but, as troll1995 has mentioned above, the syntax of Greek is very flexible and it's not always possible/meaningful to include every word order imaginable because that would lead to exercises having a huge amount of alternate sentences, especially if that was done for every sentence in the course. As with other exercises, this one, too, is correct with the pronoun at the end of the sentence and it's a matter of emphasis.

[MercedesEm13]

δεν θυμάμαι ο τι έχω κάνει. Λάθος είναι; Γιατι;Ευχαριστώ

[D_..]

Ό,τι or ότι? I'm guessing you mean the first because of the space, and mizinamo has already answered that (timestamp shows 1 year ago). ;)

[NigelKJ]

My mistake for not checking but the dotted I do not remember suggests Δε θυμάμαι.

[BenjaminDe540650]

Why is "δεν θυμάμαι που έχω καμει" incorrect?

[jurgen_maes]

δεν θυμάμαι ό, τι έχω κάνει

[D_..]

Please read the previous comments. :)