once
gb/wˈʌns/ us/wˈʌns/
A2
英语
~ 1000
义项
0 个义项
adverb
A2
relation
1
One single time in the past
Used to say something happened only one time before now.
用法模式：
[someone/something] once [verb]
常见错误：
Learners sometimes confuse 'once' with 'one time' in formal writing; 'once' is often preferred for brevity.
近义词
formerly (More formal, often referring to a previous state rather than a single event.)
反义词
often (Describes something happening many times instead of just one.)
搭配
once before
|only once
|just once
|once again
|once more
主题
time
|daily life
|core_vocabulary
例句
- I once met a famous actor at the airport.
- She once lived in Paris before moving to London.
- He once told me he wanted to be a pilot.
- They once owned a small cafe in the city.
- We once went camping in the mountains.
学习者例句
- I once saw a lion at the zoo.
- She once worked in a big office.
- He once played football for his school.
- We once ate dinner at that restaurant.
- They once visited my house.
adverb
B1
relation
2
At some point before now
Used to talk about any time before now, especially in negative sentences.
用法模式：
if/when [someone/something] once [verb]
常见错误：
Learners may mistakenly use 'once' here to mean 'one time' when the meaning is 'at all before now'. Context decides.
近义词
ever ('Ever' is more general and can refer to the past or future, while 'once' here is limited to the past.)
反义词
always (Means happening at all times instead of never or only at some past time.)
搭配
never once
|not once
|once in my life
主题
time
|core_vocabulary
例句
- Not once did he complain about the long hours.
- If she once trusts you, she will tell you everything.
- Never once have I regretted my decision.
学习者例句
- I have not once been to Japan.
- He never once called me.
- She has not once eaten sushi.
conjunction
A2
relation
3
As soon as something happens
Used to say something will happen right after another thing happens.
用法模式：
once [clause], [clause]
常见错误：
Learners sometimes confuse 'once' with 'one time' here. In this meaning, it connects two events in time.
近义词
when ('When' is broader; 'once' emphasizes immediacy after the first event.)
反义词
before ('Before' indicates an earlier time instead of after.)
搭配
once you start
|once it is done
|once we arrive
主题
time
|core_vocabulary
例句
- Once you finish your homework, you can watch TV.
- I knew I had made a mistake once I saw her face.
- Once the sun sets, it gets cold quickly.
学习者例句
- Once I eat, I feel happy.
- You can play once you clean your room.
- Once we get there, we will rest.
adverb
B1
relation
4
At a former time, not now
Used to say something was true before but is not true now.
用法模式：
[someone/something] was once [adjective/noun]
常见错误：
Learners may confuse this with 'one time'; here it means 'in the past but not now'.
近义词
formerly ('Formerly' is more formal and used mainly in writing.)
反义词
currently (Means true at present instead of only in the past.)
搭配
once famous
|once beautiful
|once a leader
主题
time
|core_vocabulary
例句
- She was once a celebrated singer, but now she lives quietly.
- This area was once full of farms, but now it's all houses.
- He was once my best friend.
学习者例句
- I was once very shy.
- This place was once a park.
- She was once my teacher.
语法
相关表达
once and for all
1/wˈʌns ˈænd fɚ ˈɔl/
fixed phrase
finally and completely ending something
To do something one final time so it is finished forever.
例句
- Let’s settle this once and for all.
- He quit smoking once and for all.
once and for all
2/wˈʌns ˈænd fɚ ˈɔl/
fixed phrase
Finally and completely ending something
To do something so it will never need to be done again.
例句
- Let's settle this argument once and for all.
- He fixed the problem once and for all by replacing the whole system.
once in a while
1/wˈʌns ˈɪn ə wˈaɪl/
fixed phrase
Occasionally, not often
Sometimes, but not often.
例句
- We go out for dinner once in a while.
- I like to read a novel once in a while.
- Once in a while, I like to take a long walk alone.
- We meet for coffee once in a while to catch up.
once upon a time
1/wˈʌns əpˈɑn ə tˈaɪm/
fixed phrase
literary
Traditional story beginning phrase
A phrase used at the start of old stories to mean 'a long time ago'.
例句
- Once upon a time, there was a small village by the sea.
- Once upon a time, there was a little princess who loved to sing.
- Once upon a time, a brave knight lived in a faraway land.
- Once upon a time, people traveled by horse and carriage.
once bitten, twice shy
1/wˈʌns bˈɪtən | twˈaɪs ʃˈaɪ/
idiom
Cautious after bad experience
After something bad happens, you are careful not to let it happen again.
例句
- I won't lend him money again—once bitten, twice shy.
- I don’t lend money anymore—once bitten, twice shy.
- She avoids online shopping now; once bitten, twice shy.
- She avoided dating for years; once bitten, twice shy.
once bitten, twice shy
2/wˈʌns bˈɪtən | twˈaɪs ʃˈaɪ/
idiom
Cautious after bad experience
After something bad happens once, you are more careful next time.
例句
- I won't lend him money again—once bitten, twice shy.
- She was hurt in her last relationship and is now once bitten, twice shy.