You can picture possibly as a word that opens a door just a crack: it says 'this might be true / might happen' without promising it. It marks the space of what is possible — not certain, but not ruled out. Once you hold that 'the door is , it could go either way' image, the surprised, polite, and emphatic uses all turn out to be that same door pushed in different directions.
原始詞典資料2 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
possiblyadv/ˈpɒs.ə.bli/
- 1
Perhaps; indicates that the proposition may be true (is not certainly false) regardless of any facts or circumstances known to, stated by or implied by the speaker.
- Near-synonyms: maybe, perhaps, mayhap, mayhaps, by chance, perchance, peradventure; conceivably
- Possibly, they will make gains in the midterm elections.
- 2
In the realm of possibility; indicates that the action may successfully be performed (is not impossible) regardless of any facts or circumstances known to, stated by or implied by the speaker that might limit the performance.
- I'm much stronger than you, so you can't possibly win.
- I couldn't possibly be there on time.
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。