The bedrock of something is the principles, ideas, or facts on which it is based. 根本原则；基础；基石；
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Mutual trust is the bedrock of a relationship…
互信是交往的基石。
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Working-class voters form the bedrock of Labour’s support.
工薪阶层选民是支持工党的基本力量。
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//…the bedrock principles of British democratic socialism.
英国民主社会主义的根本原则