Tā zhīshì yuānbó, xiàng yīběn huó de bǎikē quánshū.
He is very knowledgeable - like a living encyclopedia.
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usage
百科 is short for 百科全书 (encyclopedia). Standalone 百科 is commonly used in product names (百度百科 = Baidu Baike, China's Wikipedia equivalent) and in compounds. The full 百科全书 means a comprehensive reference work covering all fields of knowledge.