Why it has a negative effect in old age, however, isstill a mystery, although a study carried out by Clare MacKay at the University of Oxford in 2009 offers a tentative, hypothesis.

但为什么它在老年有负面影响仍然是一个谜。 牛津大学的克莱尔·麦凯（Clare MacKay）在2009年进行的研究提供了一个试探性的假设。

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However, a follow-up study conducted by the same researchers found that the type of book most frequently checked out of each of the public libraries in Leeville was the mystery novel.

但是，由相同的研究人员所作的一项跟踪调查却发现，每个公共图书馆外借得最频繁的图书均为志怪小说类。

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A follow-up study by the same researchers found that mystery novels were the most frequently checked out books from each of the public libraries in Leeville.

由相同的研究人员所作的一项跟踪调查则发现，志怪小说是Leeville市每个公共图书馆外借频率最高的一类图书。

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