23. 助动词 have 的用法 1 ) have + 过去分词,构成完成时态, 例如: He has left for London. 他已去了伦敦。 By the end of last month, they had finished half of their work. 上月未为止,他们已经完成工作的一半。 2 ) have + been + 现在分词,构成完成进行时 ,例如: I have been studying English for ten years. 我一直在学英语,已达十年之久。