过去式 有规则的也有特殊的，特殊的都是要记的。
规则的主要分为：1直接加ed
2双写加ed
3把y化i加ed
4以e结尾的直接加d
特殊的要靠死记，常用的有：(1) AAA型（动词原形、过去式、过去分词同形）
单词过去式：
规则的：return-returned，学习ask-asked
,play-played,jump-jumped,walk-walked,climb-climbed,turn-turned,teach-teached,learn-learned,row-rowed,watch-watched,wash-washed,look-looked,plant-planted,help-helped,work-worked,cook-cooked,clean-cleaned,open-opened answer-answered,listen-listened,teach-teached pick-picked
不规则的：is-was,are-were,swim-swam,fly-flew,buy-bought,go-went,do,does-did,sing-sang,have-had,write-wrote,get-got,write-wrote,find-found,think-thought, become-became,
come-came,drive-drove,take-took,send-sent,eat-ate,study-studied,draw-drew,meet-met,fall-fell,wake-woke,fight-fought,sleep-slept,
加-d的：dance-danced,use-used,love-loved,close-closed,live-lived
是原型的：read-read,let-let,put-put,
