abstract.tex

\documentclass[thesis.tex]{subfiles}
\begin{document}
% ************************** Thesis Abstract *****************************
% Use `abstract' as an option in the document class to print only the titlepage and the abstract.
\begin{abstractTH}
สำหรับเขียนบทคัดย่อ
\end{abstractTH}

\begin{abstract}
This is where you write your abstract ...
\end{abstract}

\end{document}