Breakdown of Habt ihr daran gedacht?
haben
to have
ihr
you (informal plural)
daran
about it / of it
denken
to think
Questions & Answers about Habt ihr daran gedacht?
Why does the past participle of denken (to think) become gedacht?
The verb denken is a "mixed" verb. It mixes the rules of regular and irregular verbs: it gets the normal ge- at the beginning and -t at the end, but the vowel in the middle changes from an e to an a.
What is daran, and why don't we just say "über es" or "an es" for "about it"?
In German, the verb denken pairs with the preposition an (to think at/on something). When you want to say "about it" for a thing or an idea, German doesn't usually say an es. Instead, it combines da and an to make the compound word daran.
Why does the sentence use Habt ihr instead of Hast du?
ihr is the informal plural "you" (like "you all" or "y'all"). The helping verb haben (to have) is conjugated as habt to match ihr. If you were asking just one friend, you would say: Hast du daran gedacht?
Why is gedacht at the very end of the sentence?
In the spoken past tense (Perfekt), the sentence forms a "bracket". The helping verb (habt) comes first in a yes/no question, and the main action verb in its past participle form (gedacht) is pushed to the very end.