Building and exporting a small car from Wuhu to the United States will be a challenging exercise in logistics.

The shaft rescue is another challenging exercise.

This was a challenging exercise, as Arrian noted:

Studying shallow sub-tidal environments can be a challenging exercise, especially among shifting sands.

Inevitably, deconstructing the titles of individual papers was a challenging exercise in itself.

This has been a fascinating and very challenging exercise in really entering public life through our home.

Both of these books also offer challenging exercises.

The entire battle group had trained the previous six months in preparation for this deployment through a series of increasingly challenging exercises and operations.

But identifying the rest of the stars turned out to be one of the more challenging exercises of the voyage.

They thrive with hunting or comparable challenging exercise for an hour or more every day.