adj.难以置信的，惊人的，非常好(或坏、极端)的，难以相信的，不真实的

The news that he won the lottery was unbelievable.
他中了彩票的消息令人难以置信。
It's unbelievable how much the city has changed in just a decade.
这座城市在短短十年间的变化之大真是难以置信。
She finished the marathon in under three hours – that's just unbelievable!
她在三小时内完成了马拉松比赛，这简直难以置信！
He claimed to have seen a UFO – I found that quite unbelievable.
他说他看到了不明飞行物，我觉得这很不可思议。
The athlete's strength and endurance are simply unbelievable.
那位运动员的力量和耐力简直令人难以置信。
The quality of this painting for a first-timer is unbelievable.
对于一个初学者来说，这幅画的质量令人难以置信。
The story about his escape from prison is so unbelievable that many doubt its truth.
他越狱的故事如此离奇，以至于许多人怀疑其真实性。
The speed at which technology advances nowadays is unbelievable.
如今科技发展的速度之快令人难以置信。
She learned to play the piano in just six months – an unbelievable achievement.
她只用了六个月就学会了弹钢琴，这是一个令人难以置信的成就。
Despite the odds, they managed to save the endangered species – truly unbelievable.
尽管困难重重，他们还是成功挽救了这个濒危物种，真是一件了不起的事情。