分词分为过去分词和现在分词，是非谓语动词，但分词又和谓语动词又可以相互转化，分词到谓语仅一步之遥。过去分词表示被动、完成的含义，起修饰作用，作定语、状语和补语，比如：the work done by John。如果过去分词前加上have则为谓语动词表示完成含义，现在完成用have done，过去完成用had done，将来完成用will have done，我们只需要改变done前的have的形态就可以表达不同的完成含义，比如：He has finished his work. He had finished his work. He will have finished his work；done还可以用来表示被动含义，只需要在其前面加上be动词（am, is, are, was, were），就变成了谓语动词。比如，The work is finished. The work was finished. The work will be finished. The work has been finished. The work will have been finished. The work had been finished. 现在分词表示主动进行，起修饰作用，做定语、状语和补语，比如：the boy sitting under the tree。如果现在分析前加上be动词，则为谓语动词表示进行含义。如：He is doing his homework. He was doing his home work. He will be doing his homework. He has been doing his homework. He had been doing his homework. He will have been doing his homework.