Questions & Answers about Was hat er gedacht?
Why is the past participle gedacht instead of "gedenkt"?
gedacht comes from the verb denken (to think). It is a "mixed" verb. Like regular verbs, it uses the ge- prefix and a -t ending. But like irregular verbs, the letters in the middle change. The stem denk changes to dach, making the participle gedacht. It is very similar to how "think" becomes "thought" in English!
Why is hat used here instead of a form of sein?
To form this past tense, you need a helping verb. Most verbs, including denken (to think), use haben (to have). Because the subject is er (he), the correct conjugated form is hat. We generally only use sein (to be) for verbs that show movement from one place to another or a change of state.
Why is gedacht at the very end of the sentence?
In German, the two parts of the past tense create a "sentence bracket." The helping verb (hat) sits in the normal verb position right after the question word (Was). The past participle (gedacht) is then pushed all the way to the very end of the sentence.
The English translation says "What did he think?". Does this sentence also mean "What has he thought?"