Back 【解題】觀察 4+0 和 0+9 這二個算式 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. 【解題】觀察 4+0 和 0+9 這二個算式 上傳學習單 下載學習單