How to tell if a species is a Bronsted acid, base, or both

[starrios]

Homework Statement
Identify the following species as a Bronsted acid, base, or both

a) HI
b) CH3HOOH
c) H2PO4-
d) HSO4-

I don't need the answers-- those are in the back of the book. I just don't understand how to classify each species. Thanks in advance for any help!

 

[Borek]

What are the Brønsted acid/base definitions?

 

[starrios]

Acid is a proton "donor", Base is a proton "acceptor".