动词原形 过去式 过去分词
do did done
study studied studied
go went gone
clean cleaned cleaned
stay stayed stayed
visit visited visited
have had had
don't didnt
isn't wasn't
动词原形 过去式 过去分词
do did done
study studied studied
go went gone
clean cleaned cleaned
stay stayed stayed
visit visited visited
have had had
don't didnt
isn't wasn't