While there are signs that a mushroom is poisonous, they are not consistent, and all mushrooms of unknown origin should be considered dangerous to eat.

尽管有特征说明蘑菇是有毒的，但它们是不一致的，所有来历不明的蘑菇都应该被认为是有危险的食物。

youdao

This truck is of unknown origin.

这辆卡车来历不明。

《新英汉大辞典》

The investigation of an outbreak of unknown origin in Angola has revealed extremely high levels of bromide in plasma sampled from several affected patients.

对安哥拉暴发的来源不明疫情的调查显示，从一些受影响患者身上提取的血浆样本中溴化物含量极高。

youdao

The medical examiner said a contributing factor in Lee's death was "cachexia of unknown origin, " or malnutrition.

CNN: STORY HIGHLIGHTS

Unlike newspapers though, which are of unknown origin, each track in Undersound will have a birth-place, giving added meaning.

ENGADGET: Undersound, a way to trade music on the London Underground

This expulsion was instead the result of an abrupt-onset stomach ailment of unknown origin that left me doubled over in my office for most of Monday morning.

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