%\usepackage{subfigure} % 導入下面兩個包 而不是 subfigure
\usepackage{caption}
\usepackage{subcaption}
參考
https://www.overleaf.com/learn/latex/How_to_Write_a_Thesis_in_LaTeX_(Part_3)%3A_Figures%2C_Subfigures_and_Tables#Subfigures
https://tex.stackexchange.com/questions/200994/environment-subfigure-undefined-on-journal-submission