So which has been most challenging for you and why?
As one might imagine, architectural innovations are the most challenging for incumbents to pursue.
Most challenging for such a simulation is the generation of necessary boundary conditions.
It is in Syria where this dynamic is most acute and most challenging for the United States.
Most challenging for me was riding between two logs, placed parallel and close together to simulate a deep rut.
This is most challenging for structure determination experiments, making it valuable to develop reliable computational structure prediction methods.
The bill is perhaps most challenging for Mr. Vallone, who at 66 finds himself at the crossroads of his long political career.
Life chances for young minority ethnic people have got worse over the past five years and are "the most challenging for generations".
The area that looks most challenging for Mr Cameron is freedom of movement and the rights to benefits of migrant workers.
"Die Meistersinger," with characteristic perversity, saves the best and the most challenging for last, and as midnight approaches at the Metropolitan Opera, everyone is tired.
Perhaps this is most challenging for those whose inclination is to speak, like politicians, who more than ever now are using Twitter as a virtual megaphone.
