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ビュッフェ行ったら女性のワンピース率が高くて…
→ “I went to a buffet and the rate of women wearing one-piece dresses was so high that...”
ビュッフェ byuffe = buffet (n.)
行ったら ittara = if I go / when I go (v.)
行 i = go
っ = small tsu (consonant gemination marker)
た ta = past tense auxiliary
ら ra = conditional particle
女性 josei = woman / female (n.)
女 jo = woman
性 sei = sex / gender
の no = of / possessive particle (particle)
ワンピース wan pī¹su = one-piece dress (loanword n.)
率 sitsu = rate / percentage (n.)
が ga = subject marker particle (particle)
高くて takakute = because it is high / since it is high (adj.)
高 taka = high / tall
く ku = adverbial form (conjunctive)
て te = connecting particle (linking verb/adjective)
… = ellipsis (punctuation)