<p>Between a.d 350 and 550, kolomoki, (in what) is now Georgia, (was one of ) the largest and (most densely) populated towns north of pre-columbian Mexico. (No error)</p>
<p>(Contrasting) a resume, a cover letter allows job applicants (to write in) a (more conversational) style and to suggest (their) possible contributions to a company’s success. (No error)</p>