載入中... 相關課程 Back tough: 困難的;堅強的;堅硬的;嚴格的 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. tough: 困難的;堅強的;堅硬的;嚴格的 上傳學習單 下載學習單