2. In the following expressions, “ $\bigcirc$ ” and “ $\square$ ” represent two different operation symbols. Think about which symbols can be filled in to make both equations true at the same time:
$$
1 \bigcirc 9 \bigcirc 1 \square 9=19 ; 8 \square 3 \square 3 \bigcirc 8 \bigcirc 3=83 \text {. }
$$
$2.1+9+1 \times 9=19$;
$$
8 \times 3 \times 3+8+3=83 \text {. }
$$