In each of the following reactions, decide whether the underlined species is functioning as a Bronsted-Lowry acid or base. Explain.
a. HE+H2O=H3O+F (HE underlined)
b. H2O+S2=HS+OH (S2 underlined)
c. H2O+H2CO3=H3O+HCO3 (H2CO3 underlined)
d. HCO3+H2O=H3O+CO3^-2 (HCO3 underlined)