这要看“我和妹妹”作主语还是宾语。做主语时,楼上诸位说的很清楚。作宾语时,则应该是:me and my sister.例如: He walked me and my sister home. 他步行送我和妹妹到家
sister有姐妹的意思~~楼上几位都差不多如果更确切一些的话~~应该是My little sister and I
地道的说法是Me and my little sister.或者是My little sister and I.
My sister and i