1. For the set $\left\{x, x^{2}-x\right\}$, the range of values for $x$ is ( ).
(A) $(-\infty,+\infty)$
(B) $(-\infty, 0) \cup(0,+\infty)$
(C) $(-\infty, 2) \cup(2,+\infty)$
(D) $(-\infty, 0) \cup(0,2) \cup(2,+\infty)$
-.1.D.
By the mutual distinctness of the elements of the set, we know that $x$ should satisfy $x \neq x^{2}-x$.
In fact, if $x=x^{2}-x$, then $x=0$ or $x=2$. Therefore, the range of values for $x$ should be all real numbers except 0 and 2.