распределите глаголы в 3 колонки в зависимости от чтения окончания ed.
{t} {d} {id}
Covered,trained, completed, researched,wanted, complained, proposed, fixed, demonstrated, looked, designed, traveled, asked, depended, stopped, finished, closed, opened, worked.

t-researched, fixed,looked, asked, stopped,finished, workedd-covered, trained, complained, proposed, designed, traveled, closed, openedid-completed,wanted, demonstrated, depended