An unknown object would appear in the sky.

一个未知的物体会出现在天空中。

This is an unknown object or structure which is pulling galaxies, including our own, towards it.

这是一个未知的物体或结构，正在将包括我们自己在内的星系拉向它。

U.S. media reports said a U.S. nuclear-powered submarine collided with an unknown object in international waters in the South China Sea on Oct. 2, causing many injuries.

据美国媒体报道，10 月 2 日，美国一艘核潜艇在南中国海国际水域与不明物体相撞，造成多人受伤。

While They drank to celebrate the arrangement, Mrs Corney told Mr Bumble about old Sally's death, and the unknown gold object which she had stolen from the dead body of The young woman.

他们举杯祝贺这一安排，这时，科尼太太将老萨莉的死和她从死去的年轻女人身上偷了不知名的金货的事一起告诉了班布尔先生。