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alternately; by turns
子供たちは代る代る滑り台で遊んでいた。
The children were playing on the slide alternately.
メンバーが代る代る意見を述べる形式で進行した。
The meeting proceeded with members expressing opinions alternately.
看護師が代る代る患者の様子を見に来ていた。
Nurses came alternately to check on the patient.