  In this paper, we propose and study a model, in which there exists only one
basic neutrino. Basically, the Lagrangian of the model is obtained from the
Lagrangian in the Glashow-Weinberg-Salam electroweak theory by reducing the
three flavor neutrinos there to one basic neutrino. In this model, neutrino
states with a fixed flavor are interpreted as certain superpositions of states
of the basic neutrino and states of the related charged lepton. Neutrino mass
states are associated with low-lying eigenstates of the total Hamiltonian. We
derive an approximate expression for a ratio of neutrino-mass differences,
which gives a value $17$ for the ratio, about half of the experimental result
of $33$.
