Dear Priscilla,
ola.yes, I agree, but, I don't really speak Portuguese well, and I understand few words . When I come here, I bring dictionary with me and when I saw a dictionary in Belas Shopping, I bought another one.
Why? because it is really necessary and very important to understand and to speak Portuguese here, otherwise,you will be lost.
It is with big pleasure for me to learn , speak and write Portuguese.Like carlosfmsilva wrote, it is mandatory.