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first experience (of something)
first sexual experience
雪を見るのは初体験だった。
Seeing snow was my first experience.
飛行機に乗るのは初体験で、ドキドキした。
Flying on an airplane was my first experience, and I was thrilled.
プロの厨房での初体験は、忘れられない思い出となった。
My first experience in a professional kitchen became an unforgettable memory.