Please include the regurlar expression for each and draw a fa for each as well.

Show that the following languages are regular.

$1$a$.L=\{a^n|n3\}$ where $=\{a\}$

$2$a$.L=\{\begin{array}{c}{a}^n|n0\end{array}$ and $\{$:$n3\}$ where $=\{a\}$

$3$a$.L=\{\begin{array}{c}{a}^n|n\end{array}$ is either a multiple of $3$ or a multiple of $5$