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shy; diffident; retiring; reserved
新入社員は遠慮勝ちに質問した。
The new employee diffidently asked a question.
彼女は遠慮勝ちな態度で、おかわりを断った。
She, with a reserved attitude, declined a second helping.
遠慮勝ちなので、彼はなかなか意見を言えない。
Because he is diffident, he can hardly state his opinion.