体细胞突变是柑橘等果树比较常见的生物学现象，也是品种选育，即芽变选种的主要变异来源。

Somatic mutation, a main biological phenomenon of citrus and other fruits, is often used for breeding as a major variation source. Spontaneous mutations often occur in citrus.

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本文对原发性进行性失语（PPA）进行了分类，而且还介绍了其3种主要变异，旨在增强病例报告的统一性并提高研究结果的可靠性。

This article provides a classification of primary progressive aphasia (PPA) and its 3 main variants to improve the uniformity of case reporting and the reliability of research results.

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咳嗽变异性哮喘属于哮喘的一种，其主要症状是干咳。

Cough-variant asthma is a type of asthma in which the main symptom is a dry, non-productive cough.

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