Final answer:
The word 'bien' should be used to fill in the blank in the sentence 'Yo juego'.
Step-by-step explanation:
The correct word to fill in the blank is bien. This is because the sentence 'Yo juego' translates to 'I play' in English, and 'bien' means 'well' or 'good' in Spanish. Therefore, the correct sentence would be 'Yo juego bien', which translates to 'I play well' or 'I play good'.
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