When should the personal a be used in a sentence and y

Don't use it when the direct object is an inanimate object.
This preposition is called the personal a because we only use it when referring to human beings! With any other direct object, it's totally superfluous. Compare these two sentences: Yo veo a una chica.
JUST GIVE ME POINTS ITS NOT HARD

1. subjuntivo2. indicativo3. subjuntivo4. subjuntivo5. indicativo6. c7. a

For this question, it will be important to use the words "mejor" (better), "lo mejor" (the best), and "lo peor" (the worst). while "mejor" is comparative (you are comparing one thing to something else), "lo mejor" and "lo peor" are superlative (there is nothing else better or worse than what these words are describing - there is no comparison).  you could say something like: la música rap es mejor que la música clásica - que es lo peor - pero la música rock es lo mejor de todas las formas de la música (rap music is better than classical music - which is the worst - but rock music is the best out of all the forms of music).