Give a regular expression for each of the following languages.

a.{abc}

d.{ax | x {a, b}*}

g.{x {a, b}* | x contains at least three consecutive as}

i.{x {a, b}* | x starts with at least three consecutive as}

o.{(ab)^n} u {(aba)^n}

q.{x {a, b}* | the number of as in x is odd}

u.{xy {a, b}* | the number of as in x is odd and the number of bs in y is even}