The issue with the second usage is that "matter-of-factly" means "in a matter-of-fact style"; it is not synonymous with "as a matter of fact".  "As a matter of fact" is by itself already an adverbial phrase (meaning "actually"); tacking an additional -ly on the end to re-adverbialize it can't be right.

I'd be more inclined to express your friends' apparent intended meaning as "I don't know personally" or "I don't know directly".

Is the following usage of "matter-of-factly" correct?
I am using xelatex and want to use the xeCJK package, but without indenting the first paragraph of a section. I tried the setup directive below, which should do the trick. But it does not. The manual is in Chinese ...

\documentclass{article}


\usepackage{xeCJK}
\setCJKmainfont{SimSun}
\xeCJKsetup{indentfirst=false}


\begin{document}

\section{Section 1}

I want to have a paragrpah without indentation.

This one should be indented.

\subsection{Section 2}

Same here.

This one should be indented.


\end{document} 

