Chapter 16.12, Problem 1CP

Which of the following cannot act as a Lewis base? (Select all that apply.)

$\begin{array}{l}\text{a)}\hfill \\ {\text{NH}}_{\text{3}}\hfill \\ \text{b)}\hfill \\ {\text{OH}}^{\text{-}}\hfill \\ \text{c)}\hfill \\ {\text{CH}}_{\text{4}}\hfill \\ \text{d)}\hfill \\ {\text{Fe}}^{\text{2+}}\hfill \\ \text{e)}\hfill \\ {\text{Al}}^{\text{3+}}\hfill \end{array}$