But they have found it difficult to establish the magnitude of the aerosol cooling.
Without this environment, it is extremely difficult to establish the plants.
When they are somebody else's children, it may be more difficult to establish the same relationship.
The British Bankers Association which chairs the joint money laundering steering group, said yesterday it was sometimes notoriously difficult to establish the beneficial owners of accounts.
Oakden, who is leading the investigation into what happened, said the conflicting accounts could make it difficult to establish the truth.
In terrorism cases it is very difficult to establish the motive, to find the eyewitnesses, to complete the cross-examination, etc.
Astronomers found it difficult to establish the likelihood that all these events would have occurred, and the discovery of Charon provided information that further refuted the theory.
It is always more difficult to establish the abuse in those circumstances.
Thus, it is difficult to establish the correlation between governing parameters and response of the bridge.
It is difficult to establish the accurate and fixed error model for the inertial sensor.
But the trade is so poorly regulated that it is extremely difficult to establish the true source of the skins.
