Structure for showing possession or relationship
S + 是 + [N/đại từ] + 的 + NUse '的' to show possession or a relationship. '的' attaches to the noun for the person or thing and comes before the main noun. For example, '爸爸的书' means 'dad's book'.
他是我的哥哥。
He is my older brother.
她是我妈妈的朋友。
She is my mom's friend.