Questions & Answers about Es necesario que vayas a la embajada hoy.
Why is the verb vayas used here instead of vas?
The phrase Es necesario que (It is necessary that) expresses a requirement, which triggers the subjunctive mood for the action that follows. Vayas is the subjunctive form of ir (to go). If you used the normal present tense vas, it would just be a statement of fact: you are going.
Where does the 'y' come from in vayas?
Why do we use a la embajada instead of en la embajada?
In Spanish, the verb ir (to go) always expresses movement toward a destination, so it is followed by the preposition a (to). You only use en (in/at) when talking about a static location, like estoy en la embajada (I am at the embassy).
Is it okay to include the pronoun and say que tú vayas?