= Solution
The <Clausius statement of the second law> forbids a cyclic device whose sole effect is transfer of <heat> from a colder <thermal reservoir> to a hotter one. The <Kelvin-Planck statement of the second law> forbids a cyclic device whose sole effect is complete conversion of <heat> drawn from a single <thermal reservoir> into <work>. These are equivalent formulations of the <Second law of thermodynamics>; an ordinary refrigerator is allowed because supplied <work> is an additional effect.
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