I keep encountering situations where I would like to quickly include a few "fill-in-the-blank" style underlined horizontal spaces (usually within an enumerated environment) but each time I come to search the tex.SE, all I find in searches are more specific or advanced applications. Even when I use the "questions that may already have your answer" and "similar questions" I don't find anything that addresses this specific case.
It seems to me I should be able to make this happen relatively easily, without necessarily loading a new package (if that's what's best, then that's what's best, but I'm trying to learn how to build up expressions myself, instead of always relying on existing packages), but I can't seem to make it happen.
Until now, I have not posted the question, because I've assumed I'm just not using the right language, but this is the 4th or 5th time that I've done this, so I figure I can't be the only one not finding the result.
Basically, I just want something that behaves like
\newcommand{\myBlank}{\underline{\qquad\qquad\qquad\qquad}.}
or
\newcommand{\myBlank}{\underline{\hspace{5cm}}.}
except, instead of a constant length, have it expand to the remaining space on the current line (i.e. until the end of line).
I tried using glue (which I only recently discovered, and know very little about), but that didn't seem to work, either:
\newlength{\myBlankSp}
\setlength{\myBlankSp}{10cm plus 10cm minus 15cm}
\def\myBlank{\underline{\hspace{\myBlankSp}}}
Any simple solutions? Again, both interested in understanding how to create it, but also ensuring that a simple answer (ideally not just calling a package) is actual findable on the SE, as it seems both useful and as though it's the type of issue that can teach you something important about the way LaTeX works.