现在，“青年隐蔽”的病因还不明确，但媒体通常报道说欺凌、考试不及格或者找不到工作之类的创伤性事件导致了这一问题。

And while it’s not clear exactly what causes hikikomori, traumatic events such as bullying, failing a test or not getting a job are often reported as triggers.

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超声心动图通常被用来诊断心室和瓣膜异常，对任何呼吸困难病因不明确的病人均可采用。

Echocardiography is usually diagnostic of abnormal ventricular or valvular function and should be performed in any patient in whom the cause of dyspnea is not readily apparent.

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克罗恩病和溃疡性结肠炎统称为炎症性肠病(IBD)，病因虽不明确，但对其发病机理已有了较多的了解。

Crohn s disease and ulcerative colitis, collectively known as inflammatory bowel disease (IBD), the etiology is not clear, but its pathogenesis has had more understanding.

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