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every person; every mouth
every entrance
参加者が口々に意見を述べた。
The participants each spoke their opinions one after another.
子供たちが口々に答えを叫んだ。
The children each called out answers at the same time.
避難者たちは口々に地震の恐怖を語り始めた。
The evacuees each began to speak of their fear during the earthquake.