Chapter 14.2, Problem 7PP

Identify the reactant that is a Brønsted-Lowry acid and the reactant that is a Brønsted-Lowry base in each of the following:
$\begin{array}{l}\text{a}\text{. HI}(aq)+{\text{H}}_2\text{O}(l)\to {\text{I}}^{-}(aq)+{\text{H}}_3{\text{O}}^{+}(aq)\hfill \\ \text{b}{\text{. F}}^{-}(aq)+{\text{H}}_2\text{O}(l)\rightleftarrows \text{HF}(aq)+{\text{OH}}^{-}(aq)\hfill \\ \text{c}{\text{. H}}_2\text{S}(aq)+{\text{C}}_2{\text{H}}_5-{\text{NH}}_2(aq)\rightleftarrows \hfill \\ {\text{HS}}^{-}(aq)+{\text{C}}_2{\text{H}}_5-{\text{NH}}_3{}^{+}(aq)\hfill \end{array}$