does,doing,did
goes,going,went
watches,watching,watched
washes,washing,washed
reads,reading,read
swims,swimming,swam；
has,having,had
flies,flying,flew
takes,taking,took
eats,eating,ate
gets,getting,got
studies,studying,studied
sings,singing,sang
buys,buying,bought
sees,seeing,saw
关于fly的过去式,确认为flew,很认真的检验,