一般来说 have / has 后面不直接加动词原形；当“有”讲时，后面加名词，如 I have a book ；用作助动词，构成现在完成时时，后面加过去分词，如 I have finished my homework/ She hasfinished her...have/has/had+动词的过去分词表示现在完成时和过去完成时