| Her echo bounced from wall to wall, penetrating his ears like an unsolvable riddle. |
| I think this is an unsolvable problem, and I might start with an attempted proof of its unsolvability rather than a solution. |
| It also solves a number of supposedly unsolvable problems that Web service developers have discussed over the years. |
| Assumptions of the world as fair and manageable are shattered by an unsolvable mystery that can go on for a lifetime. |
| They pursue impossible dreams, work ridiculous hours, and resolve unsolvable problems. |
| We can see symptoms of this when specialists get bogged down in apparently unsolvable general questions. |
