Поставить глаголы в форме Present Participle и Past Participle.
to see
to feel
to sit
to work
to do
to understand
to discus
to know
to smell
to cry

Present Participle Simple: seeing, feeling, sitting, working, doing, understanding, discussing, knowing, smelling, crying.Present Participle Perfect: having seen, having felt, having sat, having worked, having done, having understood, having discussed, having known, having smelt, having criedPast Participle: seen, felt, sat, worked, done, understood, discussed, known, smelt, cried