buy bought bought
send sent sent
lend lent lent
be （am ,is 的过去式是 was are 的过去式是were.过去分词都是been)
go went gone
fly flew flown
sit sat sat
teach tought tought
understand understood understood
think thought thought
make made made
get-got-gotten
spend-spent-spent
write-wrote-writen
ring-ring-rung
come-came-come
have-had-had
paid-paid-paid
sell-sold-sold
bring-brought-brought
leave-left-left
sweep-swept-swept
see-seeing-saw-seen
take-took-taken