have的用法：
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。
扩展资料
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。
have +been +过去分词，构成完成式被动语态。
例如：
English has been taught in China for many years. 中国教英语已经多年。
