1. Given the polynomial in $x$ and $y$: $x^{8} y - x^{m^{2}-m} y^{2} + x y^{4}$, which is arranged in descending powers of $x$. Then the number of integer values of $m$ is ( . )
(A) 2
(B) 4
(C) 6
(D) 8
一、1. B.
According to the problem, $1<m^{2}-m<8$, and $m^{2}-m$ is the product of two consecutive integers, so $m^{2}-m=2,6$.
Solving this, we get $m=2,-1,3,-2$.