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in unison
in unison 是固定短语，作状语，表示“一起、同时、齐声”。
They answered the question in unison.
他们齐声回答了这个问题。
一起；同时
unisons — plural of unison
先理解核心含义，再看它在真实句子里的用法。
一起；同时
acting or happening together at the same time
They answered the question in unison.
他们齐声回答了这个问题。
常用于 in unison
两个音符或声音音高相同；同时演奏相同音高(或相隔八度)的音符。
Identical pitch between two notes or sounds; the simultaneous playing of notes of identical pitch (or separated by one or more octaves).
与另一个音高相同的音或音符,尤指用作音程的基础音；同音弦
A sound or note having the same pitch as another, especially when used as the base note for an interval; a unison string.
和谐一致的状态；协调同步。
The state of being in harmony or agreement; harmonious agreement or togetherness, synchronisation.
两个或更多声音同时说或唱相同内容；齐声。
Two or more voices speaking or singing the same words together.
The choir sang the final verse in unison, creating a powerful sound.
合唱团齐声唱出最后一段歌词，营造出有力的声音。
The children answered the teacher's question in unison, "Yes!"
孩子们齐声回答老师的问题：“是的！”
The dancers moved in perfect unison, as if they shared one mind.
舞者们动作完全一致，仿佛心有灵犀。
in unison 是固定短语，作状语，表示“一起、同时、齐声”。
They answered the question in unison.
他们齐声回答了这个问题。
in unison with 后接保持一致的人或事物，多用于正式语境。
The board acted in unison with the shareholders.
董事会与股东行动一致。
Not this
The class answered the question at unison.
Use this
The class answered the question in unison.
表示“齐声、一致地”时，unison 必须与介词 in 搭配，写成固定短语 in unison；不能按“at the same time”的搭配类推成 at unison。
Not this
They sang the national anthem in a unison.
Use this
They sang the national anthem in unison.
in unison 是固定短语，unison 在此表示抽象概念，不用冠词 a/an；即使还有其他可数用法，这个习语中也不能加 a。
Not this
The children recited the poem unison.
Use this
The children recited the poem in unison.
unison 是名词，不能直接放在动词后作状语表示“齐声地”；表达“齐声/一致地”需要介词短语 in unison，不能照中文“齐声”直接省略介词。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
齐声；一起；一致地
The crowd cheered in unison when the winner appeared.
当获胜者出现时，人群齐声欢呼。
行动一致；协同行动
The team acted in unison to complete the project on time.
团队协同行动，按时完成了项目。
异口同声地说；齐声说
The students spoke in unison, reciting the pledge.
学生们齐声背诵誓词。
齐唱；齐声歌唱
The children sang in unison at the concert.
孩子们在音乐会上齐声歌唱。
与……一致；与……和谐
His actions were in unison with his words.
他言行一致。
齐声地；一致地
The crowd chanted the slogan in unison.
人群齐声高喊口号。
行动一致；协同行动
The rescue teams acted in unison to save the survivors.
救援队协同行动拯救幸存者。
齐声歌唱
They sang the national anthem in unison at the ceremony.
他们在仪式上齐声高唱国歌。
Use unisons naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
想象 uni-（一）+ son（声音）：所有声音合成一个，就是齐唱、一致。
语域：mixed 常见场景：music、formal writing、everyday conversation unison 的语域因义项而异：表示“齐唱/齐奏”时多用于音乐语境，较正式；短语 in unison 表示“一起/一致”时在日常和正式场合都常用。
unison /ˈjuːnɪsən/ 没有常见的完全押韵词。以 uni- 开头的词（uniform、unicorn、university）与前半部分 /juːnɪ/ 发音相同，可帮助记忆。注意以 -son 结尾的词（person、lesson、reason）拼写相似，但重读元音不同，并不押韵；其中 -son 可能读作 /sən/ 或 /zən/。
Dictionary facts from ECDICT, OCTANOVE, WIKTIONARY.