Sorry I can't write in Chinese, but I just understood what you are asking:) Besically, 自動詞 don't and can't take an object marked by を。On the other hand, 他動詞 needs an object. (If a sentence with 他動詞 lacks object, we consider it's dropped.) ＊Only one exception(as far as I know) is [place]を+movement verb, such as 歩く、飛ぶ、渡る。道を歩く、空を飛ぶ、横断歩道を渡る。These are 自動詞. The place is not object; it's just place where the movement takes place. ＊Some verbs can work both as自動詞and他動詞。 「カラオケで　歌う（自動詞）」 「カラオケで　ドラえもんの歌を　歌う（他動詞）」