編譯overleaf時出現了這個錯誤：
求助於 overleaf 的support staff，很快（不到1個小時）就得到了答復郵件，內容如下：
Hello, Thanks for getting in touch! The complete error actually looks like this:
And the actual command that has not been defined is "\XMUT@value@chairman". (Similarly for \XMUT@value@appraiser i.e. the next error.)
This is because this particular template requires these values, but you have commented out the lines for \chairman and \appraiser in author.tex. Therefore if you re-enable these, the error messages will go away. Even if you need to leave the names blank, you would still need to write \chairman{} and \appraiser{}. I hope this helps. Best, LianTze — Dr. LianTze Lim Overleaf TeXpert
原來是在 author.tex 這個文件中的， \chairman{XXXX} 和 \appraiser{XXXX} 被我注釋掉了。
然而，這兩個值不可缺省，因此，不想要里面有內容的話，放空就可以了。
問題得到解決，感謝林蓮枝博士~