I"m with my sister.为什么要加am

I"m with my sister.为什么要加am i'm with my sister Gina.为什么要加am呢? I am with my sister I am with my sister等于my sister and “i am looking for my father with my sister” 是什么意思? 为什么i am wanna be with you要加am I my in lisa with last the photo am sister with,my,swimming,sister,am,i连词成句 I am going to HONGKONG with my sister. i'm going to the supermarket with my mother为什么要加with I'm going shopping with my sister,划线提问with my sister I am ( )( )( )my little sister