Aircraft Flight Operation Regulations Article 78
All flight crew members shall use breathing oxygen continuously whenever the cabin pressure altitude is above 10000 feet.
中文原文 航空器飛航作業管理規則第78條
全體飛航組員於艙壓高度超過一萬呎飛航時，應持續使用氧氣。
English translation for reference only; the Chinese text prevails. Not legal advice.