We know that the Quantum Chromodynamics (QCD) fails at low energies. For example, within QCD, we cannot calculate precise mass and spin of nucleons. It does not concern the Scale-Symmetric Theory (SST). Moreover, experimental data show that at low energies the effective range parameters for nn, np, and pp scatterings are similar, but different. Why? Here, applying SST, we calculated the effective range parameters and scattering lengths for nn (respectively 2.732 fm and -18.806 fm), for np (2.778 fm and -23.867 fm), and pp (2.824 fm and -16.995 fm). These theoretical results are consistent with experimental data. At low energies, the effective range parameters follow from exchanges of virtual pions (which are responsible for the nuclear strong interactions) and production of the virtual condensates (which are responsible for the nuclear weak interactions at low energies). The condensates insignificantly increase the effective ranges. Just at low energies, the effective range parameters for nucleons follow from their strong-weak interactions described within SST. On the other hand, the scattering lengths we interpret as the circumferences of the produced gluon/photon loops with maximum radius. The obtained here and within SST results show that QCD is the incomplete and partially incorrect theory - the same concerns the electroweak theory at low energies.