C422 Of course they were familiar

"Sister A Ying, you're familiar, of course you're familiar with each other," Zhang Shaoyang said. "When I was young, Sister A Ying and my elder sister would often take me out to play, so I would often follow behind their butt … Sigh … In fact, Sister A Ying was pretty good. She was an only child and didn't have a brother. Her relationship with my elder sister is like iron