Examples of systems which cannot receive work adiabatically?

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In Principles of General Thermodynamics, Hatsopoulus and Keenan (p 442) make the following claim:
if a system is in such a state that it cannot receive work adiabatically, it is in equilibrium.
What, however, would be some physical examples of such a system?
 
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A piston with ideal gas as a working fluid in thermal equilibrium with an infinite reservoir. If you do constant pressure compression work on the piston, the gas gets colder, so there's an irreversible flow of heat into the cylinder from the reservoir. The opposite is true if you do expansion work. Either way, doing work on the system results in heat flow in/out of the system in an irreversible manner. The irreversibility is the key to understanding this claim. Remember that thermodynamic equilibrium is a state of maximum entropy.