/ækt ||; ækt/noun[C] 1 a thing that you do 所做之事；行动: In a typical act of generosity they refused to accept any money. 他们真的是慷慨，不肯收钱。to commit a violent act 动粗；施暴
Act and action can have the same meaning It was a brave act/action. Act, not action can be followed by of It was an act of bravery. Activity is used for something that is done regularly I like outdoor activities such as walking and gardening. act 和 action 可以用来表示相同的意思：It was a brave act/action. 这是英勇的行为。act 后面可以接 of，但 action 不可：It was an act of bravery. 这是英勇行为。activity 指经常做的事：I like outdoor activities such as walking and gardening. 我喜欢户外活动，例如散步和园艺。 2 oftenAct one of the main divisions of a play or opera （戏剧的）一幕: How many scenes are there in Act 4? 第4幕有多少场？
3 a short piece of entertainment, especially as part of a show （尤指综合表演中的）小节目: Did you enjoy the clowns' act? 你喜欢那些小丑表演的节目吗？
4 oftenAct a law made by a government 法律条例；法令: The government passed an act forbidding the keeping of guns. 政府通过一项法令禁止私藏枪支。
5 behaviour that hides your true feelings 掩饰真实感情的行为: She seems very happy but she's just putting on an act. 她看似很快乐，但只是装出来的。
a hard act to follow→
HARD¹
be/get in on the act become involved in an activity that is becoming popular 参与或加入某项时髦的活动
get your act together to organize yourself so that you can do sth properly 妥作安排以便办好某事；使出劲来:
If he doesn't get his act together he's going to lose his job. 他不使劲就会失去工作。 in the act (of doing sth) while doing sth, especially sth wrong 正在做某事（尤指坏事）的时候；当场:
He was looking through the papers on her desk and she caught him in the act. 他正在翻阅她桌子上的文件的时候被她逮个正着了。