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A calculation method by the improved three-fluid model is shown to describe phenomenologically temperature and frequency dependence of surface resistance Rs for high-Tc superconductors. It is verified that this model is useful to describe temperature dependence of Rs for such high-Tc superconducting films as Y-Ba-Cu-O (YBCO), Eu-Ba-Cu-O, and Tl-Ba-Ca-Cu-O films. For the frequency dependence of Rs of a YBCO bulk, furthermore, the measured results which have not depended on f2 in the frequency range 10-25 GHz, can be described successfully by this model. Finally, a figure of merit is proposed to evaluate material quality for high-Tc superconductors from the values of electron densities and momentum relaxation time determined by the present model.