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。
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。
动词have/has表示"有"时,它通常有三个含义: A.表示"某人(在物质上的)所有."这种情况下不能用there be替换.如: I have a new watch. 我有一块新表. He has a good friend. 他有一个好朋友. B.表示"某人或动物(在身体上的)长有".这种情况也不能用there be替换. 如: She has blue eyes. 她的眼睛是蓝色的. A horse has two ears. 马有两只耳朵. C.表示"某物体(在结构上的)装有".这种情况可以用there be替换.如: A clock has a round face.= There is a round face on a clock. 钟上装有一个圆型的钟盘. That room has only two windows.= There are two windows in that room. 那个房间仅装有两扇窗户. The school has 14 classes. = There are 14 classes in the school. 那个学校有14个班级. D.另外,表示"某人手中有某物"时,也用have/has.例如: Mary has a glass of water in her hand. 玛丽手中端着一玻璃杯水.