Uracil -- a pyrimidine found in RNA that base-pares with adenine.

尿嘧啶--核糖核酸中的一种嘧啶，与腺嘌呤形成碱基对。

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Thymine: Organic compound of the pyrimidine family, often called a Base, consisting of a ring containing Both nitrogen and carbon atoms, and a methyl group.

胸腺嘧啶：一种嘧啶类有机化合物，通常叫做基底，由含有氮和碳原子以及甲基的环形物组成。

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