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。
3)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。