第三人称单数形式 现在分词 过去式stay - stays - staying - stayed have - has - having - haddrink - drinks - drinking - drankbuy - buys - buying - boughtpack - packs - packing - packed
第三人称单数形式 现在分词 过去式stay - stays - staying - stayed have - has - having - haddrink - drinks - drinking - drankbuy - buys - buying - boughtpack - packs - packing - packed