Spelling rules (Verbs in Past Simple and Past Participle)

To make the Past Simple or Past Participle for regular verbs:

work-worked: add -ed.
stay-stayed: add -ed.
like-liked: verbs that finish in -e, just add -d.
study-studied: consonant+y - remove y and add -ied.
stop-stopped: if verb finishes in consonant-vowel-consonant, double the final consonant.