[en] According to my own belief that “The God wouldn't create a world that is so boring that a particle knows only the very feeble weak interaction.”, maybe we underestimate the roles of neutrinos. We note that right-handed neutrinos play no roles, or don't exist, in the minimal Standard Model. We discuss the language to write down an extended Standard Model - using renormalizable quantum field theory as the language; to start with a certain set of basic units under a certain gauge group; in fact, to use the three right-handed neutrinos to initiate the family gauge group SU_f(3). Specifically we use the left-handed and right-handed spinors to form the basic units together with SU_c(3)×SU_L(2)×U(1)×SU_f(3) as the gauge group. The dark-matter SU_f(3) world couples with the lepton world, but not with the quark world. Amazingly enough, the space of the Standard-Model Higgs Φ(1,2), the family Higgs triplet Φ(3, 1), and the neutral part of the mixed family Higgs Φ⁰(3,2) undergoes the spontaneous symmetry breaking, i.e. the Standard-Model Higgs mechanism and the “project-out” family Higgs mechanism, to give rise to the weak bosons W^± and Z⁰, one Standard-Model Higgs, the eight massive family gauge bosons, and the remaining four massive neutral family Higgs particles, and nothing more. Thus, the roles of neutrinos in this extended Standard Model are extremely interesting in connection with the dark-matter world