Final answer:
The best Spanish word to complete the sentence is 'recibiste' which means 'you received' in English.
Step-by-step explanation:
The best Spanish word to complete the sentence is recibiste as it agrees with the subject 'tú' which is the second person singular form of the verb 'recibir' (to receive). The sentence would then be 'Tú recibiste un diploma la semana pasada' which translates to 'You received a diploma last week.'
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