2. Given $y=\log _{a}(2-a x)$ is a decreasing function of $x$ on $[0,1]$, the range of values for $a$ is ( ).
A. $(0,1)$
B. $(1,2)$
C. $(0,2)$
D. $[2,+\infty)$
2. B.

First, $a>0$, then $2-a x$ is a decreasing function. From the given, we get $a>1$. Also, $2-a x>0, x \in[0,1]$, then $2-a>0$, which gives $a<2$. Therefore, $1<a<2$.