4. The real root situation of the equation $\frac{1}{x}-2=x^{2}-2 x$ is ( ).
(A) It has three real roots
(B) It has only two real roots
(C) It has only one real root
(D) It has no real roots
4.C.

The original equation is transformed into $\frac{1}{x}=(x-1)^{2}+1$.
Let $y_{1}=\frac{1}{x}, y_{2}=(x-1)^{2}+1$.
In the same coordinate system, draw the graphs of the inverse proportion function $y_{1}=\frac{1}{x}$ and the parabola $y_{2}=(x-1)^{2}+1$. At this point, the solution to the equation is converted to the x-coordinates of the intersection points of the two graphs. Clearly, the two graphs have only one intersection point in the first quadrant.