載入中... 相關課程 Back necessity [nə`sɛsətɪ] n. [C] 必需的事物;必需品 相關課程 0 / 750 登入觀看 ⇐ Use this menu to view and help create subtitles for this video in many different languages. You'll probably want to hide YouTube's captions if using these subtitles. necessity [nə`sɛsətɪ] n. [C] 必需的事物;必需品 上傳學習單 下載學習單