stop -stopped
see -saw
drive -drove
let -let
catty(应该是carry吧～,carry-carried)
keep-kept
join -joined
find -found
think -thought
teach -taught
catch -caught
现在分词形式
stay -staying
begin -beginning
forget -forgetting
lie -lying
die -dying
run -running
prefer -prefering
give -giving
ring -ringing
dance -dancing
hope-hoping