  Let $p$ be an odd prime, and let $a$ be a rational $p$-adic integer with
$a\not\equiv 0\pmod p$. In this paper, using WZ method we establish the
congruences for $\sum_{k=0}^{p-1} \binom ak^2(-1)^k(1-\frac 2ak)$ modulo $p^2$
and $\sum_{k=0}^{p-1} \binom ak^r(1-\frac 2ak)^s$ modulo $p^4$, where
$r\in\{3,4\}$ and $s\in\{1,3\}$.
