So we actually know a lot. We know a lot more than we would normally know about a secret grand jury investigation.

我们了解的信息很多。就大陪审团的秘密调查而言，我们掌握的信息比通常情况下多得多。

Project Sign carried out a huge top secret investigation, but they were never able to identify the UFO as any known plane, jet, or military-grade flying object, as it was officially classified as an alien aircraft.

Project Sign 进行了一项巨大的绝密调查，但他们从未能够将 UFO 识别为任何已知的飞机、喷气式飞机或军用级飞行物体， 因为它被正式归类为外星飞机。