Memorizing Pas and Past Participle forms of irregular verbs (groups 5 to 8)

Category 2: Vowel change, irregular ending, Past form=Past Participle

group 5: vowel change , d or t ending 

creep     crept     crept
feed       fed       fed
feel        felt       felt
keep      kept      kept
kneel     knelt \ kneeled     knelt \ kneeled
meet     met       met
sleep     slept     slept
sweep   swept    swept
weep     wept     wept
leave     left       left

group 6: different pronunciation of the same vowel d or t ending 

deal       dealt                        dealt
dream    dreamed \ dreamt     dreamed \ dreamt
lean       leaned \ leant           leaned \ leant
leap       leapt                        leapt
mean     meant                      meant
read       read (/red/)             read (/red/)
hear       heard                      heard

group 7: ell turns to old

sell    sold    sold
tell    told    told

group 8: vowel change with ought (or *aught) ending d or t ending 

bring     brought         brought
buy       bought          bought
fight      fought           fought
seek      sought          sought
think     thought         thought
catch     caught           caught
teach     taught           taught