Final answer:
The correct form of the verb 'faire' to complete the sentence is 'fais'.
Step-by-step explanation:
In French, to complete the sentence 'Tu _______ une promenade,' you would use the verb 'faire' in the second person singular form, which is 'fais'.
Therefore, the correct form of the sentence would be: 'Tu fais une promenade.'
The verb 'faire' means 'to do' or 'to make,' and in this context, it is used to express someone going for a walk.
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