你好，是swim—swam—(swum)括号里的如果是现在分词，就是swimming
现在分词：swimming过去分词：swum过去式：swam
现在分词是swimming过去分词是swum
过去式:swam过去分词:swum现在分词:swimming第三人称单数形式:swims
现在分词swimming
