/rɪ'ækt; rɪ`ækt/
v
1 [I, Ipr] ~ (to sb/sth) behave differently or change as a result of sth; respond 作出反应; 回应
*Pinch me and I will react. 你要掐我我就有反应.
* People can react badly to certain food additives. 有的人对某些食物添加剂产生严重变态反应.
* react positively/negatively to a suggestion 对一项建议作出赞成的[反对的]回应
* She reacted to the insult by turning her back on him. 她受他侮辱之後就不再理睬他了.
2 [I, Ipr] ~ (against sb/sth) respond to sb/sth with hostility, resistance, etc 反对; 反抗; 反动
*react strongly against tax increases 强烈反对增税
* Will the people ever react against this dictator? 有朝一日人民会起来反抗这个独裁者吗?
3 (chemistry 化)
(a) [I, Ipr, Ip] ~ with sth; ~ (together) (of substances) undergo changes by coming into contact with sth （指物质）起化学反应
*Iron reacts with water and air to produce rust. 铁与水和空气起化学反应而生　.
* Sodium and water react (together). 钠和水能起反应.
(b) [Ipr] ~ on sth have an effect on sth or produce a change in sth 对某事物有影响; 使某事物产生变化
*How do acids react on metals? 酸对金属起什么反应?

v [I]

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1【behaviour/feelings】
2【chemicals】
3【prices】
4【become ill】
Phrasal verbs
　react against something

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【BEHAVIOUR/FEELINGS】
to behave in a particular way or show a particular emotion because of something that has happened or been said
→respondreact to
　How did Wilson react to your idea?
　He reacted angrily to the suggestion that he had lied.
　She reacted very badly (=was very upset) when her parents split up.
　You have to react quickly to circumstances.
react by doing sth
　The government reacted by declaring all strikes illegal.
→overreact
【CHEMICALS】
technical if a chemical substance reacts, it changes when it is mixed with another chemical substance
react with
　The calcium reacts with sulphur in the atmosphere.
【PRICES】
if prices or financial markets react to something that happens, they increase or decrease in value because of it
react to
　Oil prices reacted sharply (=reacted a lot) to news of the crisis in the Middle East.
　The market reacted favourably to the announcement.
【BECOME ILL】
to become ill when a chemical or drug goes into your body, or when you eat a particular kind of food
→respondreact to
　Quite a lot of children react badly to antibiotics.
react against [react against sth] phr v
to show that you dislike someone else's ideas or ways of doing something, by deliberately doing the opposite
　He reacted strongly against his religious upbringing.