vi.

1. 作出反應，反應[（+to）]
   How did she react to the news?

   她對這個消息反應如何？

2. 影響，起作用[（+on/upon）]
   The two react upon each other.

   這兩者互相影響。

3. 抗拒，反抗[（+against）]
   Children tend to react against their parents by going against their wishes.

   孩子們通常以違背父母的意願來反抗他們。

4. 起反作用，回過來起作用[（+on/upon）]
   Unkindness often reacts on the unkind person.

   惡人往往有惡報。

5. 【化】起化學作用；【物】反應[（+with/on）]
   How do acids react on metals?

   酸對金屬會起怎樣的化學反應？

   An acid can react with a base to form a salt.

   酸和鹼反應會產生鹽。

6. 【軍】反攻，反擊

vt.

1. 使起（化學）反應；使發生相互作用[（+with）]
   We make superphosphate by reacting rock phosphate with sulphuric acid.

   我們使磷酸鹽岩同硫酸發生化學反應製造過磷酸鈣。

v.

1. respond to something in a particular way.
   ▸ (react against) respond with hostility or a contrary course of action to.
2. suffer from adverse physiological effects after ingesting, breathing, or touching a substance.
3. Chemistry  & Physics  interact and undergo a chemical or physical change.
4. Stock Exchange  (of share prices) fall after rising.