（过去式无非是在后面加个ed）这句话是什么意思?大家帮忙解释下,谢谢!

并非所有的动词是在后面加个 ed 就是过去式.1.[加个 ed] want,pass,drive; learn...= want-ed; pass-ed; drive-d.learned/learnt,2.[完全变化] eat = ate; catch =caught; take = took; 3.[没有变化] run =run; hit ...