Spanish - Propositions

por

Talk about duration:

Usualmente estudio por cinco horas.
(I normally study for five hours.)

Talk about modes of transportation:

Ella prefiere ir por barco.
(She prefers to go by ship.)

Because

Él no pudo salir por la tormenta.
(He could not leave because of the storm.)

Yo no acamparé allí por la nieve.
(I will not camp there because of the snow.)

para

Talk about destinations:

Salen para España en media hora.
(They are leaving for Spain in half an hour.)

Talk about a deadline:

Necesito las invitaciones para el jueves.
(I need the invitations for Thursday.)

Talk about why you are doing something:

Tienes que salir pronto para ir a la biblioteca.

For me or for you:

para mí / para ti

a

When you talk about people in Spanish, you should always add a between the verb and the person.

Yo visito a Juan.

al and del

• del = de el
• al = a el

But de and a don't combine with la, los, las.