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opportunity; occasion; chance
買い物の序でに近くの銀行に寄った。
I stopped by the bank while shopping.
外出の序でに郵便局に寄ってきたよ。
I went to the post office while I was out.
散歩の序でに駅前の本屋を覗いてみた。
I dropped by the bookstore while taking a walk.