act
act — verb
1. to do things in a certain way, showing a particular kind of behaviour.
to do things in a certain way, showing a particular kind of behaviour.
The children acted well while their grandparents were visiting for dinner.
act + adverb for behaviour
At the interview, Mina acted calm even though her hands were shaking.
act + adjective
Why are you acting so strange around your new piano teacher?
On stage, Leo acted like a king and bowed to nobody.
- behave
the closest general synonym
- conduct yourself
more formal and often used in rules or advice
文法句型
act + adjective
act like + noun
用法筆記
Often followed by an adjective or by 'like + noun' to show the kind of behaviour. Distinguish from sense 5, which usually suggests annoying or foolish behaviour.
常見錯誤
2. to take steps instead of waiting, usually to achieve something or handle a probl
to take steps instead of waiting, usually to achieve something or handle a problem.
The town acted fast after the river rose above the bridge.
act + adverb
Seeing smoke in the kitchen, Rosa acted to keep the children outside.
act to + verb
No one acted until the teacher saw the broken window.
After weeks of delay, the company finally acted on the safety report.
文法句型
act to + verb
act on + report / advice / information
用法筆記
This sense focuses on doing something practical. Common with adverbs like 'quickly' and with patterns such as 'act to...' or 'act on...'.
常見錯誤
3. to start producing a result, especially in the body or on a material.
to start producing a result, especially in the body or on a material.
The cream acted within minutes and the baby's rash began to fade.
act within + time
The medicine acted slowly, so Mr. Lin stayed in bed all morning.
act + adverb with medicine subject
Once the heat acted on the ice, water ran across the table.
By midnight, the coffee had acted, and Nina felt fully awake.
- work
the most common everyday alternative
- take effect
often used for medicine, rules, and plans
- fail
to produce no result
文法句型
act on + body part / material
act within + time
用法筆記
The subject is often something that causes change, such as a drug, heat, pressure, or a policy. Do not confuse this with sense 6, where something acts as another thing.
常見錯誤
4. to appear as a character before an audience or camera.
to appear as a character before an audience or camera.
Ken acted the doctor in our school play last Friday.
act + role noun
In the film, Sara acted opposite a famous singer from Seoul.
act opposite + performer
During college, Omar acted in three musicals and one TV advert.
At rehearsal, Mei acted with such skill that everyone fell silent.
文法句型
act in + play / film
act + role noun
用法筆記
Often followed by 'in' for the production, or by a role noun in more formal stage language. This is the only verb sense tied to theatre and film performance.
常見錯誤
5. to make yourself look foolish, annoying, or unnatural, often to get attention.
to make yourself look foolish, annoying, or unnatural, often to get attention.
Stop acting silly and put your shoes back on.
act + adjective in commands
At lunch, Dylan acted like a boss and ordered everyone around.
act like + noun
Even at twelve, Nora still acts like a baby sometimes.
The new student acted cool, but nobody found him funny.
- fool around
more playful and informal
- show off
stresses trying to get attention
文法句型
act silly / cool / superior
act like + noun
用法筆記
Common in spoken English when criticizing someone's manner. It often suggests that the behaviour is not natural or not suitable for the situation.
常見錯誤
6. to do the job of something, or be used in its place.
to do the job of something, or be used in its place.
For one week, the spare room acted as a home office.
act as + role
In the emergency, Lena acted as team leader until noon.
act as + temporary job
A folded towel can act as a pillow on the train.
During repairs, the old bridge acted as the town's only road.
- serve as
the closest neutral equivalent
- function as
slightly more formal and common in technical writing
文法句型
act as + role
act as + substitute object
用法筆記
Almost always followed by 'as + noun'. The subject may be a person, room, object, or system that fills a role for a time.
常見錯誤
act — noun
1. something a person does, especially one seen as good, bad, or important.
something a person does, especially one seen as good, bad, or important.
Giving the driver an umbrella was a kind act on that wet night.
kind act
The simple act of opening the window made the room feel safer.
the act of + -ing
Police treated the fire as a criminal act from the start.
Her act of honesty saved the shop from a costly mistake.
文法句型
an act of kindness / violence / honesty
the act of + -ing
用法筆記
Often used with 'of' to name the kind of deed: an act of kindness, an act of violence, the act of telling the truth.
常見錯誤
2. behaviour put on to hide what you really feel or want.
behaviour put on to hide what you really feel or want.
Was Mia's laugh real, or was it only an act?
just an act
After the phone call, Ben dropped the act and sat quietly.
drop the act
The smile was an act to stop the children asking questions.
At dinner, her cheerful act fooled everyone except Aunt June.
文法句型
be just an act
drop the act
put on an act
用法筆記
Usually refers to fake behaviour rather than a single lie. Common with verbs like 'put on' and 'drop'.
3. one short item in an entertainment programme, or the person doing it.
one short item in an entertainment programme, or the person doing it.
The first act was a drummer from Kaohsiung with bright blue hair.
act = performer
After the clown act, a singer walked on with a red guitar.
clown act
Tonight's final act will perform high above the circus ring.
Their comedy act lasted ten minutes and ended with falling pies.
文法句型
a comedy / circus / opening act
the next act is ...
用法筆記
Common in concerts, circuses, and variety shows. It can mean the performance itself or the person or group performing it.
常見錯誤
4. one main section of a play, opera, or ballet.
one main section of a play, opera, or ballet.
The lights went down again at the start of Act Two.
Act + number
In the final act, the lost brothers meet beside the sea.
in the final act
During the second act, someone in row five answered a phone.
The director cut one song from the first act of the opera.
文法句型
Act One / Act Two
the first / second / final act
用法筆記
An act is larger than a scene. In printed scripts, it is often written with a capital letter and a number.
5. a written law that a legislature or parliament has formally approved.
a written law that a legislature or parliament has formally approved.
Congress passed an act to protect children working online.
pass an act
Under the new act, stores must label every imported egg.
under the Act
The judge explained how the act changed voting rules statewide.
A later act gave small farmers more time to repay loans.
文法句型
pass an act
under the Act
an act to + verb
用法筆記
This is a legal sense and often appears with a capital letter in the full official title of a law.