Alternately; by turns — indicating that people or things take turns doing something.
先生が代わる代わる授業を担当している。
Teachers take turns being in charge of the lessons.
客が代わる代わる写真を撮ってほしいと言った。
Guests took turns asking someone to take their photos.
代わる代わる意見を述べた後、結論に至った。
After everyone gave their opinions in turn, they reached a conclusion.