3. Let the set $A=\left\{\left.x|| x\right|^{2}-3|x|+2=0\right\}$, $B=\{x \mid(a-2) x=2\}$.

Then the number of values of $a$ that satisfy $B \varsubsetneqq A$ is ( ) .
(A) 2
(B) 3
(C) 4
(D) 5
3. D.
$$
A=\{x|| x|=1,| x \mid=2\}=\{-2,-1,1,2\} \text {. }
$$

It is easy to see that when $a$ takes the values $0,1,3,4$, $B$ is respectively $\{-1\},\{-2\},\{2\}$, $\{1\}$. Also, when $a=2$, $B$ is an empty set, $B \subseteq A$, so, there are 5 values for $a$.