1、stop stopped
sit sitted
stop stopped
beg begged
fret fretted
drag dragged
drop dropped
plan planned
dot dotted
drip dripped
2、study studied
try tried
copy copied
justify justified
cry cried
carry carried
embody embodied
empty emptied
marry married
3、potato
tomato
hero（英雄）
Negro（黑人）
4、radio
piano
photo
kilo（千克）
zoo