\documentclass{article}
\begin{document}
\section{Text Ligatures}
LDots\ldots, versus dots ...

A range: 1--10 gets en-dash.
In interjection --- like this --- gets em-dash.

A ``quote'' like this.
\section{Typewriter non-Ligatures}
\texttt{LDots\ldots, versus dots ...}

\texttt{A range: 1--10 gets en-dash.}
\texttt{In interjection --- like this --- gets em-dash.}

\texttt{A ``quote'' like this.}

\end{document}
