By1. The relationship between the empty set $\phi$ and the set $\{0\}$ is
(A) $\phi=\{0\} ; \quad(B) \phi \subset\{0\}$;
(C) $\phi \supset\{0\}$; (D) $\phi \subseteq\{0\}$.
This is a question about the concept of sets. This question examines the concepts that the set with no elements, the empty set, the set of the number 0 is a non-empty set, and the empty set is a subset of any set and a proper subset of any non-empty set. The correct answer is $(B)$.