In the figure the current source is $$1\,\,\angle \,0\,A,$$ $$R = \,1\,\,\Omega ,$$ the impedances are $${Z_C} = - j\,\,\Omega ,$$ and $${Z_L} = 2\,j\,\,\Omega .$$ The Thevenin equivalent looking into the circuit across $$X-Y$$ is.

In the Fig. $${Z_1} = 10\angle - {60^ \circ },\,\,{Z_2} = 10\angle {60^ \circ },\,$$ $${Z_3} = 50\angle {53.13^ \circ }.\,\,$$ Thevenin's impedance seen from $$X-Y$$ is

Superposition principle is not applicable to a network containing time-varying registors.