德望中學被爆對學生畢業影片訂下語言限制，網上流傳的「Language Standards」指引以大寫粗體列明「Cantonese is STRICTLY FORBIDDEN」，所有對白、旁白及配音只准使用英語或普通話；選用普通話則必須加上英文字幕。另一頁更寫明，一旦聲軌被發現含有廣東話，相關班別須將該段聲音靜音並重新處理音效。
其中最受關注的一項規定涉及學生向中文科老師致謝。指引特別寫明「When thanking Chinese subject teachers, students must speak in Mandarin」，即學生在畢業影片中向中文老師道謝時，亦被指定必須使用普通話，並配上「proper written Chinese subtitles」。影片畫面上的所有中文同樣必須使用標準書面語，禁止使用粵語口語；廣東話僅獲准以最多一首背景歌曲形式出現，並須附英文字幕。
相關安排在網上引起討論，尤其「連向中文老師講多謝都要轉用普通話」成為爭議焦點。流傳圖片顯示，校方以「STRICTLY FORBIDDEN」形容廣東話對白，同時對中文科致謝場面另設普通話要求，使畢業影片的語言規範延伸至學生向老師表達謝意的方式。
原文節錄：
Narrator & Drama Lines: All spoken narration and voiceovers must be strictly recorded in English / Or Mandarin with English subtitles.
Cantonese Audio Warning: If Cantonese audio is detected in voice tracks, classes will be required to mute the audio and completely redo sound effects.
On-Screen Written Chinese: Every Chinese line shown on screen must be proper written Chinese (Standard Written Chinese), never spoken Cantonese dialect.
Mandarin Tributes: When thanking Chinese subject teachers, students must speak in Mandarin and provide proper written Chinese subtitles. To keep them clearly visible, please place the subtitles at the top of the video.
另一頁總結更直接寫明：
Speaking / Dialogue / Voiceovers: Cantonese is STRICTLY FORBIDDEN. You must use English or Mandarin.
(Note: If you speak in Mandarin, you MUST provide English subtitles).
Background Music: You are allowed to use a maximum of ONE background song in Cantonese or Mandarin. (Note: you MUST provide English subtitles, preferably at the top of the screen.)
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