1. Let the set
$$
A=\{x \mid a x+2=0\}, B=\{-1,2\},
$$

satisfy $A \subseteq B$. Then all possible values of the real number $a$ are $\qquad$
$$
\text { -,1. }-1,0,2 \text {. }
$$

When $a=0$, $A=\varnothing \subseteq B$, satisfying the condition;
When $a \neq 0$, $-\frac{2}{a}=-1$ or 2, solving for $a$ gives $a=2$ or -1.