Comprar un billete de ida y vuelta.
Comen
Entrenamos
Caminan
Duermes
I don’t know the last one
The translation is: I am going to a concert tonight. What time? (or what i think it is)
for this answer just put down a time like: a las ocho de la noche
hope this helped! (:
The answer is (acabe) because it refers to the fact that he has not finished his studies and when he finishes it he could finally be an astronaut.