三十年前，无烟餐厅是不可想象的。

Thirty years ago a no-smoking restaurant would have been ___unthinkable.

如今，没有电脑的生活简直是不可想象的。

Nowadays it is simply ___unthinkable to live without a computer.

对他来说，失败是不可想象的；他总是追求完美。

For him, failure is ___unthinkable; he always strives for perfection.