Write down a basis for and dimension of the linear function spaces (a) $\mathcal{L}\left(\mathbb{R}^3, \mathbb{R}\right)$,
(b) $\mathcal{L}\left(\mathbb{R}^2, \mathbb{R}^2\right)$, (c) $\mathcal{L}\left(\mathbb{R}^m, \mathbb{R}^n\right)$,
(d) $\mathcal{L}\left(\mathcal{P}^{(3)}, \mathbb{R}\right)$,
(e) $\mathcal{L}\left(\mathcal{P}^{(2)}, \mathbb{R}^2\right)$,
(f) $\mathcal{L}\left(\mathcal{P}^{(2)}, \mathcal{P}^{(2)}\right)$.
Here $\mathcal{P}^{(n)}$ is the space of polynomials of degree $\leq n$.