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making a round trip; going and returning; coming and going
round-trip ticket; return ticket
correspondence; exchanging (of letters)
keeping company (with); socializing; visiting each other
毎日の通勤で往復に二時間もかかる。
It takes two hours round trip for my daily commute.
東京と大阪の往復切符を駅で買った。
I bought a round-trip ticket between Tokyo and Osaka.
往復はがきで参加の申し込みをした。
I applied using a round-trip postcard.