watch--watched,wash--washed,clean--cleaned,play--played,visit--visited,cook--cooked,study--studied,learn--learned,dance--danced,climb--climbed``````
不规则变化
do--did,got--get,fly--flew,swim--swam,see--saw,is/am--was,are--were,make--made,sweep--swept
buy--bought,ride--rode,eat--ate,take--took,sing--sang,leave--left,go--went,have--has