first task as a scanner designer is to turn each token into a regular expression.

First, describe what you want to write as RE in English. Then, give the RE for it$.$

e$.$g$.\{$a$^$n b$^$m $|$ n $>=0$ and m $>=1\}$

English: $0$ or more a$\text{'}$s followed by $1$ or more b$\text{'}$s; shortest is $$b$$

RE: a$^*$ b$^+$

Alphabet is $\{$a$,$b$\}$ for all of the following. OK to use e for empty strings.

A$)\{$a$^2$n b$^2$m$+1|$ n $>=0$ ; m $>=0\}$

Describe the language completely in English without using n or m: $*??*$

RE for it: $*??*$

B$)\{$w $|$ w has at least one pair of consecutive a$\text{'}$s $\}$ only a$$s and b$$s allowed in w

Describe the language completely in English, noting the shortest string: $*??*$

RE for it: $*??*$