不明飞行物

例句：

1. 1. The government has been investigating the mysterious disappearance of the unidentified flying object.
   政府一直在调查这个不明飞行物的神秘失踪事件。
2. 2. Many people believe that unidentified flying objects are alien spacecraft.
   许多人相信这些不明飞行物是外星人的太空船。
3. 3. The unidentified flying object was spotted over the city during a routine flight test.
   在一次常规飞行测试中，这个不明飞行物被目击于城市上空。