核心畫面
You can picture react as always the second move, never the first. Something arrives — a piece of news, a remark, a drug, another chemical — and whatever it lands on does not stay as it was; it gives something back. So behind every react there is a thing that came first, usually introduced by to (react to the news), and react names the answering change. It never describes the opening move.
可以想成 react 永遠是「第二個動作」，不會是第一個：先有東西撞進來——一句話、一則消息、一種藥、另一種化學物質…更多收起
可以想成 react 永遠是「第二個動作」，不會是第一個：先有東西撞進來——一句話、一則消息、一種藥、另一種化學物質——然後被撞到的那一方就不再維持原樣，它會回過來給出一個變化。所以用 react 的時候，句子背後一定有個先來的東西，常常用 to 帶出來（react to the news），而 react 講的是後面那個回應。主動先出手的那一步，永遠不叫 react。原始詞典資料7 筆記錄
以下是外部詞典記錄的用法，原文照列，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。
reactverb/ɹiːˈækt/
- 1
To act in response.
- How did she react to the news?
- 2
archaicTo act or perform a second time; to do over again; to reenact.
- It is somewhat extraordinary, that the offence for which James II, was expelled, that of setting up power by assumption, should be re-acted, under another shape and form, by the parliament that expelled him.
- 3
natural-sciencesphysical-sciencesphysicsTo return an impulse or impression; to resist the action of another body by an opposite force
- Every body reacts on the body that impels it from its natural state.
- 4
chemistrynatural-sciencesphysical-sciencesTo act upon each other; to exercise a reciprocal or a reverse effect, as two or more chemical agents; to act in opposition.
- 5
chemistrynatural-sciencesphysical-sciencesTo cause chemical agents to react; to cause one chemical agent to react with another.
- 6
To post a reaction (icon or emoji indicating how one feels about a posted message).
reactnoun/ɹiːˈækt/
- 1
An emoji used to express a reaction to a post on social media.
- Sad reacts only
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。