\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.

?`Espa\~nol? !`Hola!

\section{Ignore comments}
%foo
`%bar
`Hopefully Quoted%baz
'%qux
'

A number
\ensuremath{%foo
  12345.%bar
%baz
  67890%qux
}
?

An --- emdash, 
%foo
-%bar
-%baz
-%qux
perhaps?

\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}
