分规则变化和不规则变化两种.不规则变化需逐个记忆,规则变化遵循以下原则：
(1) 一般情况下,在动词后加ed构成：work / worked, stay / stayed, shout / shouted等.
(2) 在以-e结尾动词后只加d：close / closed, like / liked, live / lived, smile / smiled等.
(3) 以辅音字母加y结尾的.动词,应将y改为i 再加-ed：study / studied, carry / carried等.
(4) 以重读闭音节或r音节结尾且末尾只有一个辅音字母动词,要双写末尾的辅音字母再加-ed：stop / stopped, admit / admitted, refer / referred, prefer / preferred等.