載入中... 相關課程 Back strength: 優點, 強項, strengthen, 強化, 使變強 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. strength: 優點, 強項, strengthen, 強化, 使變強 上傳學習單 下載學習單