1. Let $f(x)$ satisfy the conditions:
(1) $f(x)=f(-x+4) \quad x \in \mathrm{R}$,
(2) When $x>2$, $f(x)$ is an increasing function. Then the size relationship of $a=f\left[(1.1)^{0.9}\right], b=f\left[(0.9)^{1.1}\right], c=f\left[\log _{\frac{1}{2}} 16\right]$ is
$c>b>a ;$