Answer
$\not \subseteq$
Work Step by Step
$A \subseteq B$ if all elements of set A are also elements of set B.
Note that an element of the set on the left ($0$ in particular) is not an element of the set on the right This means that the set on the left is NOT a subset of the set on the right.
Thus, the missing expression in the blank is $\not \subseteq$.
