How to output items such as "Question 1." and "Question 2." in the enumerate environment.

For example, use the enumitem package and input the following to hoge.tex.

......
\usepackage{enumitem}
......
\begin{enumerate}[
  label=\textrm{Question \arabic*.},
  leftmargin=0pt,
  itemindent=\dimexpr\labelwidth+\labelsep]
 \item \label{one} \ref{one} is Question 1.
 \item \label{two} \ref{two} is Question 2.
\end{enumerate}
......

See also
https://tex.stackexchange.com/questions/122698/start-the-content-of-an-item-on-a-new-line-after-the-item-label-in-enumerate-env https://stackoverflow.com/questions/34212242/latex-how-to-refer-to-the-items-text-inside-enumitem