The difficulty of finding organs suitable for transplantation on man must be met.
I should point out, however, that at first some difficulty was experienced in observing the phenomena predicted by the theory, owing to the extreme smallness of the variations in the period of oscillation.
As newly created P2P businesses disrupt the status quo and compete with established companies, they face the difficulty of fitting a square peg into a round hole when it comes to existing regulatory regimes that don't contemplate their business models.
The United States Postal Service has a problem. People aren't sending as much mail as they used to. That means less postage revenue and difficulty paying the bills.
We excuse our sloth under the pretext of difficulty.
Mine is a European imagination, shaped largely by my very promiscuous reading in German, French, English and, with greater difficulty, Italian.
It is expected that a children's story will raise a difficulty and then resolve it: increasingly, this resolution is so prompt and so resounding that one forgets what exactly the difficulty was.
On the basis of the familiar experience that that which is learned with difficulty is better retained, it would have been safe to prophesy such an effect from the greater number of repetitions.
The difficulty of writing a second novel is directly proportional to how successful the first novel was, it seems.
A major difficulty is that the answer to the Riddle of the Sphinx is partly a product of the answers that we already have given to the riddle in its various forms.
Rocket science has been mythologized all out of proportion to its true difficulty.
One mustn't close one's eyes to difficulty and to shortcomings; the more one recognizes them, the less they upset one.
They must therefore not spoil Alexander's undertaking, especially when they were almost at the close of their toils, and were, moreover, no longer in any difficulty about provisions on their coasting cruise.
Little Sparta is a garden in the traditional sense. It is perhaps not like other modern gardens, but I think that other times would have had no difficulty with it.
Everyone has talent at twenty-five. The difficulty is to have it at fifty.