A teacher wants her $N$ students to know each other, so she creates various clubs of three people, so that each student can participate in several clubs. The clubs are formed in such a way that if $A$ and $B$ are two people, then there is a single club such that $A$ and $B$ are two of its three members. (1) Show that there is no way for the teacher to form the clubs if $N = 11$. (2) Show that the teacher can do it if $N = 9$.