It should be hablé since if it talking about someone else. If it were to be you, however, the sentence would be “Yo hablo con Juan.” Comprende?
Answer:
usted
Explanation:
usted is more formal. if not certain which to use, use usted instead of tú considering its better to be more formal than less formal.
the three 3 reactants needed for photosynthesis is light energy or source (same thing), water, carbon dioxide.