"You are drinking."
In English, to mean that an action is in progress at the time you speak, you use the continuous verbal form, ie verb BE + action verb in the gerund form (-ing). o you are drinking means you currently drink
In French, this verbal form does not exist (directly translated “tu es buvant” is incorrect). Therefore, you can translate either “tu bois” or “tu es en train de manger”, where the construction verb être + en train de + infinitive correctly expresses the English continuous form.
I don't understand everything you've said. I don't know what a construction verb is nor an 'infinitive'. But I do understand that the English continuous verbal form doesn't exist. Thanks for the info :)