原词-三单形式-现在分词-过去式
teach-teaches-teaching-taught
write-writes-writing-wrote
sit-sits-sitting-sit
look-looks-looking-looked
dance-dances-dancing-danced
swim-swims-swimming-swam
put-puts-putting-put
read-reads-reading-read
say-says-saying-said
watch-watches-watching-watched
eat-eats-eating-ate
talk-talks-talking-talked
wait-waits-waiting-waited