\documentclass[12pt]{report}
\usepackage{graphicx} 
\title{\huge Analog IC Design Homework 2}
%\usepackage{xeCJK}
\author{\\\\\\\\\\\\\\\\\\EE17\\Student ID: 102061112\\Name: Po-Yang Hsieh}

\date{\today}
\begin{document}
\maketitle
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\baselineskip=24pt

\begin{enumerate}

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\begin{enumerate}
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Design:\\
M1 size($W/L$) = $8.5u/1u$ \\
When Vin = 412mV, Vout = 0.9V
\begin{center}
\includegraphics[scale=0.4]{2a_vout.png}\\
\end{center}
The ac gain
\begin{center}
\includegraphics[scale=0.4]{2a_acgain.png}\\
\end{center}
\item
\end{enumerate}

\end{enumerate}

\end{document}