keep kept kept

sleep slept slept

sweep swept swept

6、原单词end改为ent即可变为其过去式和其过去分词的动词

lend lent lent

spend spent spent

send sent sent

7、过去式和过去分词以aught/ought结尾的动词

bring brought brought

buy bought bought

catch caught caught

fight fought fought

think thought thought

teach taught taught

8、过去式与过去分词同样的动词

build built built

feed fed fed

feel felt felt

find found found

hang hung hung

hanged hanged

have/has had had

hear heard heard

hold held held

lay laid laid

learn learned/learnt learned/learnt

leave left left

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