Let $E_n$ be a D11: Set for each $n \in \mathbb{N}$ such that
(i) | $\bigcup_{n \in \mathbb{N}} E_n$ is a D77: Set union for $\{ E_n \}_{n \in \mathbb{N}}$ |
Then
\begin{equation}
E_1
\subseteq \bigcup_{n \in \mathbb{N}} E_n, \quad
E_2
\subseteq \bigcup_{n \in \mathbb{N}} E_n, \quad
E_3
\subseteq \bigcup_{n \in \mathbb{N}} E_n, \quad
\ldots
\end{equation}