动词过去式分为两类：规则与不规则规则(加ed)：work原形； worked过去式; 不规则：do原形 did过去式用途：用来表示一般过去时He came last night.He worked for two hours.一个句子中有两个过去式，并列时才会出现。He came last night and worked for two hours.
