adj.不可思议的，难以想象的，难以置信的

The idea of humans living on Mars was once unthinkable, but now it's becoming increasingly plausible.
人类在火星上居住的想法曾经是难以想象的，但现在越来越有可能成为现实。
The scale of the disaster was unthinkable, leaving entire communities devastated and in need of urgent aid.
灾难的规模之大令人难以想象，导致整个社区被摧毁，急需紧急援助。
For many, the notion of giving up their smartphones for a week is simply unthinkable.
对许多人来说，一周不使用智能手机的想法简直是无法接受的。
It's unthinkable that such a reputable company would engage in unethical business practices.
如此有声望的公司会参与不道德的商业行为，这是难以置信的。
The speed at which technology is advancing is unthinkable to those who lived just a century ago.
技术发展的速度对于一个世纪前的人来说是难以想象的。
The possibility of humans traveling back in time was once considered unthinkable in scientific circles.
在科学界，人类时间旅行的可能性曾经被认为是不可思议的。
For her, missing her child's first steps was unthinkable; she rearranged her entire schedule to be there.
对她而言，错过孩子迈出第一步是无法想象的；她重新安排了所有日程以确保能到场。
The transformation of the abandoned factory into a vibrant art space seemed unthinkable until it actually happened.
废弃工厂变成充满活力的艺术空间，这在实际发生之前似乎是不可想象的。
The notion that artificial intelligence could surpass human intelligence was once unthinkable, but now sparks heated debates among experts.
人工智能可能超过人类智能的想法曾经被认为是不可能的，但现在却在专家中引发了激烈的讨论。
That a small startup could challenge industry giants within a few years was unthinkable, yet they proved everyone wrong with their innovative approach.
一家小型初创企业在几年内挑战行业巨头的想法曾被视为不可思议，但凭借其创新的方法，他们证明了所有人都是错的。