This is no unsolvable problem if we face it wisely and courageously.
There have been unsolved mysteries, but no man may say when a crime is unsolvable.
What perplexity, when we attempt to solve an unsolvable problem!
"So that a man's life is an unsolvable riddle to all but himself," concurred the hakeem.
There still remained the unsolvable problem of what she was to do.