$1=\{|0+\}$ and $=\{,,\}$

$2\mathrm{.}2)2=\{|03\}$ and $=\{,\}$

$2\mathrm{.}3)3=\{|++$ is odd $\}$ and $=\{,,\}.($Hint: consider the cases where n$,$ m$,$ i are all

odd, or two of them are even, one is odd, etc$)$

$2\mathrm{.}4)4=\{$All odd length strings over $=\{,\},$

$\}$