  The Keldysh's theory of superfluidity of rarefied electron-hole gas is
generalized to a case of possible pair polarizability. It was shown that
inhomogeneity of the system leads to dipole moment which is proportional to the
density gradient. The dipole moment appears also near boundaries of the system.
It was determined that quantized vortices in a magnetic field carry a real
electric charge. In He II at H=10 T and helium rotation velocity $10^2$
s$^{-1}$ the charge density is about $10^4e$ cm$^{-3}$, where $e$ is the
electron charge.
