Final answer:
The past tense of the question 'does he sleep soundly?' is 'Did he sleep soundly?'. The present format changes from 'does sleep' to 'did sleep' in past tense.
Step-by-step explanation:
The question 'does he sleep soundly?' is in the present tense. If you want to change this to the past tense, you have to change the auxiliary verb 'does' to 'did' and eliminate the 's' in 'sleeps', as the past tense does not usually require this ending. So the past tense of the question would be 'Did he sleep soundly?'
Learn more about Past Tense