Learn Dutch: Ik heb dat al een keer gedaan. - I have already done that once.

In Dutch, when you use a two-part verb tense like the present perfect (I have done), the helping verb (heb) takes the second position in the sentence, and the past participle (gedaan) is pushed to the very end. Everything else goes in between!

The translation says 'once', but doesn't een keer literally mean 'a time'?

Exactly! In Dutch, een keer literally translates to 'one time' or 'a time,' which is the most common way to say 'once.' You could also use the word eens, so Ik heb dat al eens gedaan would mean the exact same thing.

Why does dat come before al een keer? Can I say 'Ik heb al een keer dat gedaan'?

No, that would sound unnatural. In Dutch, specific direct objects, especially pronouns like dat (that), het (it), or hem (him), almost always come before time adverbs like al (already).

Is gedaan an irregular verb?

Yes, it is the past participle of doen (to do). Because doen is an irregular verb, its past participle doesn't follow the standard rules of adding a -t or -d at the end. You just have to memorize that doen becomes gedaan.