7. For the odd function $f(x)$, when $x>0$, the function $y=f[f(x)]$ is $\qquad$ (fill in the monotonicity).





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7. Increasing Function
$x_{1}>x_{2}>0$ so $-x_{1}f$ $\left(x_{1}\right)>f\left(x_{2}\right)$ so $f\left[f\left(x_{1}\right)\right]>f\left[f\left(x_{2}\right)\right]$ which means it is monotonically increasing.