偶尔有一个来路不明的微小光点一闪而过。

Occasionally, a tiny flicker of light passes quickly by, its source a mystery.

在任何情况下，假冒药品总是来路不明，其成分也不可靠。

But in every case, the source of a counterfeit medicine is unknown and its content unreliable.

在此之前，我用提供来路不明的意见，但他没有采取任何通知。

Prior to this, I used to offer unsolicited advice but he took no notice.

我希望我能记起雷的原话，当他急不可待地打开印刷机，看见封面上来路不明的污点时。

I wish that I could recall Ray's exact words, when he eagerly opened the box from the printer, and saw the mysterious stains on the covers.

虽然说在你想要在健身房浑汗如雨的时候，他们毫无疑问非常实用，但是穿着来路不明的防水灯笼裤足以将任何人拒之门外了吧？

While they're unquestionably useful when you want to sweat it out at the gym, being subjected to unsolicited knicker-flashing is enough to put anyone off. Right?