17. Let the function $f(x)$ be monotonic on $(-\infty,+\infty)$, and satisfy $f(x+y)=f(x)+f(y)$ and $f(1)=$ -1. If for any positive number $t$ there is $f\left(k \log _{2} t\right)+f\left(\log _{2} t-\log _{2}^{2} t-2\right)>0$ always holds, find the range of $k$.