He came out of the library, a large book under his arm.

　　原文：He came out of the library, a large book under his arm.

　　翻译：他夹着本厚书，走出了图书馆。

　　解析：这个句子中逗号后面的内容属于独立主格的一种用法，表示伴随状态，结构为名词/代词+介词短语。再送例句一枚：The soldiers dashed in, rifle in hand. 士兵们端着枪冲了进来。
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