vi.

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

   她对这个消息反应如何？

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

   这两者互相影响。

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

   孩子们通常以违背父母的意愿来反抗他们。

4. 起反作用，回过来起作用[（+on/upon）]
   Unkindness often reacts on the unkind person.

   恶人往往有恶报。

5. 【化】起化学作用；【物】反应[（+with/on）]
   How do acids react on metals?

   酸对金属会起怎样的化学反应？

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

   酸和碱反应会产生盐。

6. 【军】反攻，反击

vt.

1. 使起（化学）反应；使发生相互作用[（+with）]
   We make superphosphate by reacting rock phosphate with sulphuric acid.

   我们使磷酸盐岩同硫酸发生化学反应制造过磷酸钙。

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.